I'm in the process of moving my accounts from Nationwide to Natwest (in the UK) solely because Nationwide have given me fob-off answers on each of the three occasions I have asked them about developing a Windows Phone app. They don't even have a mobile version of their online banking site -- their "workaround", if you can even call it that, is to log into the desktop online banking site with your 4-odd-inch mobile screen. Natwest do have a Windows Phone 8 app, which gets almost unanimous praise, hence my decision.
A mobile app is as good a reason as any to base your decision on, I reckon. Bank charges and interest rates all seem pretty much of a muchness (in the UK, anyway; I'm not sure if it's different in the U.S.) and, having banked with three different banks over the last 23 years, I can honestly say that trying to base your decision on customer service and account holder reviews is futile: they're all as incompetent and morally bankrupt as each other.