I've never been a big fan of the "What If?" concept, Marvel's comics covering paths not taken. But the small lineup of new What Ifs announced at WizardCon is something I can certainly get behind.
The one I'm absolutely gonna buy is "What if Jessica Jones had joined the Avengers?" by Bendis and Gaydos. This sounds like a book no fan of Bendis' Alias can live without.
"What if Karen Page had lived?" by Bendis, Smith, and Maleev is intriguing. Smith is the writer who killed Page off in his crappy Daredevil arc, and act Bendis characterized as "drive by writing", as Smith killed a central and then got off the book, without dealing with the repercussions for the remaining characters.
"Wha' huh?" will be a humor collection of What Ifs from Bendis, Millar, Ennis, Wade, Kirkman, and others. Ennis, Bendis and Kirkman are all quite good at bringing the funny, so this should be fun.
"What if Magneto had formed the X-Men with Professor X?" by Claremont is a book I wouldn't have much interest in, but Cully Hamner is doing the art, so it'll certainly be visually impressive.
"What if General Ross had become the Hulk?" is a Hulk What If? by Peter David, and that's enough to grab my interest. Andrea Divito on art is an added bonus.
"What if Aunt May had died instead of Uncle Ben?" is a case of a topic I'm completely uninterested in… but it's written by Ed Brubaker and Cameron Stewart is doing the art. Bru is one of my top five favorite writers of the last few years, and Stewart is terrific, so this may also get my money.
"What If Victor Von Doom had become the Thing?" is the one I'm probably least interested in. Karl Kesel has a great rep, but I don't remember ever reading anything he did, and the premise just doesn't do anything for me.
Bendis talks about his books and the whole concept here.