Marvel has some good stuff collected under "Essential X-men". Also, check out Joss Whedon's run on Astonishing X-men and Schism to explain most of the stuff going on nowadays. The most recent crisis crossover Avengers vs X-men was absolutely terrible but Avengers vs X- men: Consequences (it's epilogue) was simply amazing.
Following that there was a relaunch a month ago called Marvel Now, the current flagship title is All New X-men. It's written by Brian Michael Bendis, so it alternates between "decent" and "utter crap".
The dude also wrote M-day (while being pretty horrible) is necessary along with the Dark Phoenix Saga just to understand what the hell is going on in these books.
Or just go ahead and grab every copy of Uncanny X-men that you can. That shit ties into everything...