Utilize the "broken backlink" section. Utilize the ability to isolate lost and gained links by date. Let's say you have drops around October. You could go to right before that and specifically isolate good links lost or bad links gained, etc. They also have a good amount of helpful online resources for learning how to use the tool. Great graphs show overall trends for linking domains or linking pages. Check out the ability to sort by AHREFS' quality statistics to help analyze quality/low quality links.
Ahrefs is incredibly comprehensive and straight forward. From keyword discovery to site audits I use ahrefs for all my SEO needs. It's the first SEO program I was introduced to when starting me SEM management career and has proven to be the best time and time again. I've used their competitors liker moz, SEM rush, and a couple other services- none of which have come close to stacking up.
Pros: SEMRush is a full-fledged powerhouse for SEO building strategy and SEO audits. It's pretty beefy, so I would only recommend it if you have the time and patience for SEO, as the software gives a ton of outlets in looking up actionable items for your SEO Strategy. The first thing that I really liked with SEMRush was the initial SEO audit of my site -- I was able to see what's good and what's bad about my SEO, and the quick errors or warnings for title headers and ideas for gaining more traffic was awesome. Moving on, I found their analytics just as good as Google Analytics, showing me where my traffic is coming from and where I can improve my paid search positions. I haven't used the Social or Content aspects of SEMRush but social listening looks to be baked in well and integrated nicely. If you're in the market for seeing how your organic and paid search traffic plays a part, and then strategizing in how to improve your overall position against organic search and then your competitors, I'd recommend SEMRush.