All my friends and I immediately made the switch to The Ninth Age. There were so many things that frustrated us about Warhammer - it could be so good! - and one of them was awesome models that had no real potential to compete. Another was new books making whole armies dramatically weaker or stronger. The idea of taking part in the development of the game was really appealling, too.
T9A hasn't fixed the problem of useless units yet, but I think it's got the best shot at it. I know someone people are turned off by the tournament-balance orientation it has, but since my friends and I pretty much do everything we can to grind the other guy's army into the dust, it's nice that having a fighting chance with every army is such a priority.
There are definitely things I miss about Warhammer proper (mostly about 6th and the early days of 8th). The biggest thing is probably some of the weird rules that were such expressions of army character. But overall we're all happy that we moved to 9th Age, and look at most of the large-scale changes and say, "These are just common-sense fixes to the stupid things we've talked about for years."