My suggestion about X-Men... as others have said get Astonishing X-Men in trades (1-12), and then get issues 13 and 14 and go from there. Then either find the issues or get the trade coming out here soon of X-Men: Deadly Genesis. From there you're set. Soon (I think July) the guy who wrote Deadly Genesis will be taking over Uncanny X-Men and will be continuing that story there, so that's where you can start. The adjectiveless X-Men comic will also be getting a new writer/artist at the same time, so that's a good place to start as well. And no one's mentioned it yet, but Astonishing comes out Bi-Monthly if I'm not mistaken, so there's quite a wait between issues.
And I can't get into anything outside of Marvel... so some good Marvel stuff to look into if you're interested is Runaways, Young Avengers, and New Avengers. I find those to be consistantly good reads. Also, look up the Ultimates hardback, and the Ultimates 2 trade (soon to be 2 trades). They're an alternate take on the Avengers and they're amazing. Also to go along with the New Avengers that I mentioned, pick up the Sentry trade by Jenkins. It's a great read and ties in with the New Avengers story.