These three suites overlap far more than their marketing suggests. All three do keyword research, backlink analysis, rank tracking and a site audit, and for the overwhelming majority of sites any of them would be a defensible choice. The interesting question is not which is best in general. It is which one to commit to, since the value of a suite comes mostly from the history it accumulates while you use it.
This is written from the angle I work at, which is technical SEO and indexing, so it weights the site audit and the crawl data heavily and the content marketing features lightly. If your job is mostly content planning, weight it differently and reach a different answer honestly.
Which one I would pick, by job
Ahrefs if the link graph is the thing you look at most, and if you would rather have a fast dataset than a guided workflow.
Semrush if you need breadth across SEO, paid search and competitor tracking in one place, and if more than one person who is not an SEO will use it.
Moz if the vocabulary and the learning curve matter more than the depth, or if your organisation already speaks in Domain Authority.
None of the three answers the question I get asked most, which is why a specific page is not indexed. No suite does. That comes from Search Console and from inspecting the URL, which is why the indexing guides on this site lean on those rather than on a crawler’s opinion.
Where they actually differ
The link index. This is the real dividing line. Each vendor runs its own crawler and its own retention rules, so the three indexes genuinely disagree about what links exist. Ahrefs built its reputation here and it remains the reason most people who pay for it do. The practical consequence is that cross-tool link counts are not comparable, and any argument that starts by comparing them is not an argument about your site.
Keyword data. All three model volume rather than measure it, because nobody outside Google measures it. The numbers will differ between tools for the same term and none of them is the truth. What matters is that you use one consistently, so that relative comparisons inside your own list mean something.
The site audit. Semrush’s is the broadest and the noisiest, in the sense that it flags a great deal and leaves you to triage. Ahrefs’ is tighter. Moz’s is the most readable and the least deep. For technical work, a crawl you trust matters more than the number of checks it claims, and all three will find the obvious things.
Everything else. Content tools, PPC data, local features, reporting. This is where the feature comparison tables get long and where the difference to your outcome is smallest.
What none of them can tell you
Worth being blunt, because it is the gap that costs people the most.
Why a page is not indexed. A suite can tell you a page exists and has no links. It cannot tell you what Google decided about it. That answer lives in the URL Inspection tool and in the Pages report, and the guide to reading it is crawled, currently not indexed.
Whether Google has your page at all right now. Index status in a third-party tool is inference. Checking it properly at scale is its own job, which is why the bulk URL inspection tool on this site exists and reads from the Search Console API rather than guessing.
Whether AI search engines mention you. None of the three reports this, because there is no report to consume. The measurement has to be built by hand, and the procedure is in how to track brand mentions in AI search.
How to actually choose
Three questions, in this order.
What do you open every week? Not what the tool can do, what you will use on a Tuesday. If that is backlinks, Ahrefs. If it is a mixed dashboard several people read, Semrush. If it is one report you want to understand without training, Moz.
Who else touches it? A suite used by one specialist should be chosen for depth. A suite that a client or a manager will open should be chosen for legibility, and that changes the answer.
How long will you keep it? The history is the asset. If you will switch in six months to save money, buy the cheapest thing that does the job, because you are not going to accumulate the value that makes the expensive one worth it. If you are committing for years, the ranking of the three on features today matters less than which interface you will not resent.
Then stop comparing. The most expensive mistake in this category is not choosing the wrong suite. It is spending a year rotating between trials and never building a year of data in any of them.
Ahrefs vs Moz: DR, DA and the crawler under them
This pairing usually gets argued as Domain Rating against Domain Authority. That framing is a distraction. Both scores are outputs of a link crawler, and the crawler is what you are choosing between. The useful question is whose index better reflects the part of the web you work in, and that is testable in five minutes: take a site whose backlinks you can verify by other means, check it in both, and see which is closer to what you know. It is a small sample and still more informative than either vendor’s published index-size claim.
Both scores sit on a compressed scale where the top is crowded and each step near the top is far harder than one near the bottom. Both are relative, telling you roughly where a site sits against others in the same index and nothing about what Google thinks. Three rules make them safe to use:
- Compare within one tool only. A DR and a DA are not convertible, and a difference between them is meaningless.
- Watch the trend, not the value. A score that climbed over six months is telling you something. A score of 34 on its own tells you almost nothing.
- Never buy on the metric. Paying for a link because of the seller’s score optimises the proxy instead of the thing, and it is a well-worn route to a link profile that scores well and does nothing.
One practical point in Moz’s favour: Domain Authority has escaped into general business language in a way Domain Rating has not. If the people you report to already say DA, that has real value even though the metric itself is no better. And a high score of either kind does not mean your pages are indexed. Authority is computed from links, and indexing is a per-URL decision Google makes for reasons that have little to do with it. I have looked at plenty of sites with a respectable score and a meaningful share of pages sitting at crawled, currently not indexed.
If competitor research is the actual job: SpyFu
SpyFu gets compared with Ahrefs and Semrush, but it is a different kind of product: a competitor research tool with some suite features attached, rather than a suite with a competitor module. Its distinctive angle is time. It shows what a domain has ranked for and advertised on over a long stretch, which is the fastest way to see whether a competitor’s position is new, earned slowly, or already fading. That same framing is why it feels thin if you expected a site audit and a full backlink workflow alongside.
In competitor work the three split roughly like this: SpyFu for the historical view and paid history, Semrush for organic and paid side by side with gap reports in one login, Ahrefs when the competitive question is really “who links to them and not to me”.
Whichever you use, read every competitor number as “the model thinks”. Each tool holds its own keyword set, and a competitor ranking for something outside that set is invisible to it, which is the largest single reason two tools give different pictures of the same domain. Estimated traffic is modelled position multiplied by an assumed click-through rate, and that assumption drifts furthest on results pages crowded with AI Overviews, features and ads. Paid data is reconstructed from ads the tool observed, priced with modelled cost data. None of it is a competitor’s invoice, but a term somebody pays for month after month converts for somebody, which is a stronger signal than volume.
The most useful report in any of the three is the content or keyword gap. Run it in whichever tool you already pay for before considering a second subscription, discard most of the rows, and keep the handful that describe a problem your buyers actually have.
If the budget is the question: Ubersuggest
Ubersuggest against Ahrefs is usually framed as cheap against good. The real difference is resolution. The two report largely the same categories of information, and what the price buys is depth of the link index, long-tail keyword coverage and historical depth.
The link index is the widest gap. Building and refreshing a web-scale crawler is enormously expensive, and it is the main thing the premium price pays for. If your work involves finding who links to a competitor and going after the same sources, the cheap tool shows a thinner picture and you will not know what is missing.
The long tail is where a smaller keyword database runs out. Head terms are covered everywhere. The specific, low-volume, high-intent phrase that a small site can actually win is where the budget tool is weakest, which is unfortunately the exact material a small site should be working from.
The gap is narrower than the price suggests for basic keyword ideas, rank tracking on a modest list, and a site crawl that finds the obvious technical problems.
So the deciding test is the size of the decisions. One site, your own SEO, choosing between topics rather than fighting a competitive market: the budget tool is very likely enough, and the money saved is better spent on writing. Decisions for clients, link data you have to defend, or a market where the difference between the tenth and thirtieth best keyword is worth real money: the premium tool pays for itself. A mixed setup also works, the cheap tool day to day and a month of a premium tool when a project needs the deeper link data, provided you accept that your history lives in the cheap one.
And if what you want from a suite is to find out why Google is ignoring your pages, that is not a tooling problem. It is indexing, and it starts with Search Console.
Quick answers
Can I just use the free tiers of all three?
You can, and for a single small site it is a reasonable position, but you will hit the same wall in each: the free tiers cap the row counts and hide the historical view, which are the two things that make a suite worth paying for. The more useful free stack is Search Console for your own site, which is complete and free, plus one paid suite for the competitive picture you cannot get anywhere else. Paying for three partial views of the same data is the worst of the options.
Do these tools show the same backlinks?
No, and the differences are large enough that comparing raw counts across tools is meaningless. Each runs its own crawler with its own discovery, refresh cadence and rules about what to keep, so a link present in one index can be absent from another for weeks or permanently. What this means practically is to pick one and track the trend inside it. A number that went up in your chosen tool is a signal. A number that is higher in one tool than another is not.
Which one is best for a beginner?
Semrush, on interface alone, because it walks you into a workflow rather than handing you a dataset. That is also its downside once you know what you are doing, since the guided path is slower than going straight to the report you want. Ahrefs assumes you already know what you are looking for. Moz sits between the two and is the gentlest on the vocabulary, which matters more than people admit when you are learning.
Do I need any of them if I have Search Console?
For your own site, Search Console is better than all three: it is the actual data rather than a model of it, it covers every query you appeared for, and it costs nothing. What it cannot show you is anyone else. Everything a suite adds is either competitive, which Search Console structurally cannot provide, or convenience over data you already have. Decide which of those you are buying before you compare tiers.
Does Google use Domain Authority or Domain Rating?
No. Both are third-party scores, invented by a vendor and calculated from that vendor's crawl, and Google could not use a number computed from someone else's index. They are useful as rough comparative shorthand between sites inside one tool and as nothing else.
Can I see a competitor's actual paid spend?
No, and no tool has access to it. What you can see is a reconstruction: ads observed against keywords, priced with modelled cost data. That is useful for working out what somebody is willing to pay to appear for, which is a good proxy for what converts in your market, but it is not their invoice. Use it to rank intent, not to model their budget.
Is Ubersuggest good enough for a small site?
For a site with a few dozen pages, one person doing the SEO, and no serious competitive pressure, yes. The reports are the same categories the expensive tools give you, at lower resolution, and resolution stops mattering when the decisions are coarse. Where it falls short is the long tail and the link index, so link gap work is where the cheap option is weakest.