If all prices were the same I would choose United for the TEQM. However do some searching and try to work out the return bit better over what you have. Something such as routing through IAD or ORD on a 763, or also try for a return via FRA on a 747. The UA new C looks to be on par or better than VS in every aspect except food, lounges, and seat width. However with TEQM, I would overlook those two items. If your only option is a 777 instead of VS, I'd suggest breaking down the benefits carefully.

Though the 777 C is comfortable on a day flight, would you like TEQM or a nicer seat?