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.
The library and crawl index for Ahrefs is unparalleled. If you need to know competitive landscape and build backlinks, there is not another player in this space. moz, etc doesn't come anywhere close. they do alright in other factors, but purely from a research and backlink profile perspective Ahrefs is the leader without competition. Comparison features and backlink tracking are indispensable. Good to help with estimation of traffic on potential client's websites. You can go to the table in a client meeting better prepared. This along with SEO powersuite makes a good package.
Ahrefs make use of two link updates in your website - the Fresh Index and the Live Index. Fresh Index which updates at a longer time frame. It shows the dead links on your website, giving you the chance to change or reclaim the dead link. The Live Index, on the other hand, makes link updates every 15-30 minutes. This provides you with the chance to see regular link updates on your website.