The only thing UA and QR have in common is the fact that they are both airlines. Otherwise, they operate very differently. QR does generally provide a good experience onboard, in all classes and all routes. They WANT to, and it goes beyond service (the seats, the IFE...) and it is obvious that there is a deliberate effort to providing a good onboard experience for pax. UA doesn't make that a priority.

QR has its shortfalls too - a quick look through this forum would highlight some of them.