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.
I think they could go a long way when it comes to updating the site audit tool. I think the reporting could be a bit more comprehensive when reporting the locations of issues and their in-links. Also I think you should be able to export all the results of a site audit an have them in a single spreadsheet.
Mainly keyword research, site audits, backlink analysis, and competitor research.