I am giving 5 tacos for various reasons described below. It is at least somewhere between 4 and 5 tacos depending on features set you evaluate and need.
I hesitatingly bought a code the first time when SheerSEO launched on AppSumo. At that time, my main interest was website audits and fixing issues that existed. My SEO knowledge was terrible at the time and I am still learning. What I was impressed by was how it categorized various issues and so easy to get a complete view with or without those categories being filtered.
When I tried it for an audit, a couple of things I didn't understand and if I remember correctly, I thought it was buggy. I contacted support and I got super fast response and it made sense. I was impressed.
The next time the deal was available again, I grabbed another code. I wanted more, but quite frankly, I felt it was expensive even though I did think that there was a lot of long-term value.
Fast forward to several month, I see this deal. I logged into my SheerSEO account and spent more time browsing and trying various features including their YouTube videos. I was surprised how feature-loaded SheerSEO is. Although the videos on YouTube channel are only a handful and from 2 years ago, they were super helpful. I was excited to see a feature called "Toxic Links" under Backlinks, just as an example. Their criteria may not be super scientific or even 100% accurate, but it's a guide and they tell you so.
So, I bought again to add another domain even though by now I have several other SEO tools that have been available over the last year or so.
Honestly and frankly, I have not done any comparison of SheerSEO with all the other tools. So try it yourself and make your own decision, if you are interested in just one tool trying to decide between this and others.
I also have not evaluated accuracy of the data and honestly can't vouche for it at the moment. But I trust that it is fairly decent enough for me at this time.
I am hoping SheerSEO survives and thrives for a long time and my investment pays off multiple folds. Once I get to use it more, I will be ready to do a YouTube video and/or write reviews at other platforms.
Thank you @Ayal for your hard work and bringing this tool to us!