My two cents...most of the chuff on FT is about upgrades, which I see is numbers 4 on your list.
UA is 8 months into a huge merger, but from an operations standpoint has online metrics close to premerger.
AA is likely to merge with US, which IMHO will be a year of pain once thy flip the switch.....merger Jan 2013, operational merger March 2013??????
Pick your airline based on routes from home base , my advice.