1. The airline must be safe (in Europe/US almost all are but that is not necessarily the case elsewhere)
2. The schedule must be right with regard to my timetable
3. The price must be right (it does not have to be cheap, but it must fit within certain limits)
4. On long flights there must be enough legroom
Then we come to secondary things:
5. Enough free catering with regard to the flight time
6. FF points, please
7. Free drinks
8. Lounge access
9. Better meals, amenities
10. Convenient airport

IFE plays no, absolutely no role as a selection criteria for me. None whatsoever!