I agree with Crepello about United's "inflight entertainment" - why don't more carriers offer this? I don't suppose it will be too interesting on a hop across the pond, though - much more fun inside the US!
I'd be quite happy going VS or BA in economy - if you can afford (or otherwise blag) an upgrade, then I doubt you'll be disappointed whover you fly with.
Final thought, the most important criterion for me is a non-stop (or at least direct) flight to my destination. Changing planes at O'Hare (or wherever) wastes time and greatly dimishes the chances that your luggage will be waiting for you at your destination.