1942 The Pacific Air War allowed you to fly for the US Navy or the Imperial Japanese Navy (an update also gave access to USAAF planes such as the P-40, P-38, and P-51).
Flight models and performance differences between planes seemed extremely realistic. Torpedo planes were slow and heavy handling -- good luck surviving a career in these puppies! Dive bombers were better (but learning to dive bomb accurately is not easy). Early fighters like the F4F were underpowered and had to be handled well to succeed against Zero's. The effectiveness of different types of guns was modeled.
There were single missions for all of these planes, and you could fly a campaign career as a fighter pilot, dive bomber, or torpedo plane pilot - you could even control the backseat guns in the planes that had them!
MiGMan thanks Chino