I like Virgin and we fly them exclusively whenever we can. Economy mostly, or Prem Ec when we can splurge. We got upgraded to Upper Class once though...*passes out in bliss*
I used to fly AA lots and had gold status with them, but the last two flights I took on them were so awful in every way, I just stopped.
The one time we flew BA in the past two years, it was nice. I don't remember the meal but I remember being sick and dehydrated the whole flight and the flight attendant noticed and would drop off a bottle of water or offer me a cup of tea every time she walked by. I thought that was sweet.
My parents fly KLM twice a year and they're happy.
As to others, the last time I flew a US airline (besides AA) was four years ago on United. I am horribly scared of flying and sitting by the window just makes it worse, so I always request either an isle seat or a seat in the middle section. Anyone, on a LHR/NY flight, the check-in agent I guess tried to do me a favor and moved me to a window seat without me noticing. When I saw, I went to the gate agent and explained that I was gonna have a really rough flight if I had to sit by the window and if she could please move me. They didn't have any isle seats in economy left, so she upgraded me to business class instead. Middle section too -- although for business I'd have made an exception to my no-window-seat rule.