Haven't had the chance to really try
Battle of Britain: Wings of Victory, but I keep hearing good things about it.
B-17 II The Mighty Eighth II was fun in the beginning, but got boring very quickly. And lack of proper plane numbers (I frequently RTB'd alone, or with just one plane) was an immersion killer for me. Not to mention that out of 18 planes you could had in formation, only 6 were 'alive'. And that in the only career I managed to force myself to finish I ended with over 30 kills...
IL2 was never good offline for me. AI was predictable and flew too perfect. Bomber formations were more or less fun to attack if one used the proper tactics, trigger happy gunners who shot at other bombers flying nearby killed it for me. Other things were good, more or less. But I could never 'get into the mood' as I did with some other games. On line was where it used to shine like no other...
This leaves me no choice but to put
EAW at the first place. EAW might have had repeating missions, but the overall end result accompanied with a nice atmosphere was more or less believable. Not to mention the 100+ plane battles which were epic, to say the least.
Red Baron was very good. From what I remember of it.