I am a fan of the alternate universe series we have been able to read.
The recent Age of Apocalypse by David Lapham. While I was not a fan of depowering some of the main characters I enjoyed the world he was developing.
I like how Mutant X began and I thought it had a lot of promise before spinning it's wheels to avoid cancellation.
I liked the original Exiles and how anyone could die at any time. I did not like trying to explain who the Timebroker was. To me it detracted from the story of hopping around to put right what once went wrong. Also, King Hyperion was a lot of fun to read.
I realize that Marvel has too many cooks in the kitchen when it comes to a new series but when I was younger I really wanted an alt-x book that would break from 616 and slowly become the DofP timeline with it showing the rise and domination of the Sentinels with the series 'catching up' to Uncanny 141 and 142 in the year 2013. It could have ended with the first page from issue 141.