Aces High is the best flight sim, mostly because of its technical excellence and consistency. Next to Aces High, Warbirds is rather sloppy and buggy, although there have been some fine improvements to the game.
You can get an all you can eat subscription to Warbirds for 13.95 now, so numbers are improving... you can see 90 to 150 players now even on week nights. And they have autotakeoff now so new players don't have to spend a lot of time learning how to take off, and even an auto land feature. Warbirds is trying very hard to catch up to Aces High, but they won't make it, in my opinion. Still, it can be a lot of fun. The Main Arena in WarBirds is not an arcade arena (all planes available at all times to all 3 countries) but a WW2 arena with rolling planesets. It's fun, but Aces High has its own WW2 style arena, known as the Combat Theatre.
Air Warrior, alas, is no more.
I would recommend that you stay with Aces High. Add Mitsu's sounds to the game, and enjoy. God, with those sounds, sometimes I just sit manning an ack at an airfield just to listen to the planes taking off and arriving. No kidding. They add mucho pleasure to the game.
Happy hunting, and good luck!
