The X-Men aren't that new really. And up until recently they've been pretty dull. Sure they've always had great art and even popular creators, but they haven't really deserved the top selling comic spot for quite a while now. Especially after the horrible 'return' of Chris Claremont... ugggh. I'm not hassling his original run, but his recent run was horrible and I dropped the book.
Recently though, in what seemed like yet another 'revamp' the reigns of the the X-Men were given to Grant Morrison, Joe Casey and a number of great artists. And the results were amazing. Particularly on the New X-Men by Morrison, Quitely and co. The action, art and characterisation are all there. And it actually seems like something 'new' is really happening in the X-Men. The same old tired villains and storylines aren't just being regurgitated. Continuity isn't bogging the stories down. And best of all the whole book has an cool edgy feel that makes you think that X-Men are cool and this comic is more worthy at being at the top than it has in a long time.
So, the New X-Men really is better read. But, Uncanny hasn't really hit the ground running. The writing aside, what's really holding this back is the art. There hasn't been a consistent art team on the book since Casey took over and there has even been some horrible art. But, now that Ron Garney is coming on permanently this title may once again be worthy of top spot.
So, if you've ever liked the X-Men, but don't currently pick up a title, grab the New X-Men, it's a great read, you won't be disapointed.