Ace Combat 6. Still the best one.
I'm not convinced Ace Combat 7 is even better than Hawx 2. In fact, Hawx 2 is actually quite interesting. Graphics and speed aside, AC 7 feels like a PlayStation 2 game.
The morons at Project Aces don't understand that the only problem with AC6, is that it's an Xbox 360 exclusive. It's not where the base was.