I have been using Gentoo forever (actually since around 2005). It has always worked well for me, documentation is great (though I always take a look at the Arch documentation as well), it is extremely stable (even though I run the "unstable" version (~amd64)

Th only thing that sometimes requires a bit of elbow grease is the update process (emerge @world) which can throw up large lists of "blockers", especially when some major component changes (like say the transition from python2 to python3). "eselect news" gives ample warning beforehand.

This is the reason I never advise new linux users to use it, but I also don't see myself using any different distribution.