TetraxShards
Member
For X-Factor, read Madrox #1-5, then the run of X-Factor that starts afterward. It began in 2005 and ended in 2013. I have like 20 issues of it left myself, but it's probably my all-time favorite Marvel book since I started reading. Can't recommend it enough.
I also really enjoyed Uncanny X-Force/Avengers. X-Factor is very much it's own thing, but it's definitely as good as those. Astonishing X-Men by Marjorie Liu is from the same period and also excellent.
That run of X-Factor is one of my all-time favs. Should all be on Marvel Unlimited as well.