Personally, I do not care what aircraft come out first, just so long as, eventually, we will get a decent amount of aircraft from all eras(F-15E, F-4E, B-17, P-40, MiG-15 F-105, IL-2, etc.) and a decent selection of maps (Vietnam, Korea, modern Europe, the Middle East, West/East United States, WWII Pacific theater, etc.)
*Edit: Actually, if anyone ever decides to make it I would love an F-4E next.