12 O'Clock High is a great war movie alright. But there are tons of others, and it's really hard to say which is best.
Apocalypse Now
The Bedford Incident
Patton
Flying Tigers
Tora, Tora, Tora
Cross of Iron (James Coburn, James Mason, with Sam Peckinpah directing)
Enemy At The Gates
Sahara (the one with Bogie, Bridges, and the M3 tank)
Desert Rats (not to be confused with the TV show Rat Patrol)
Tears of the Sun (I think that was it - Bruce Willis as a merc)
Full Metal Jacket (gotta love Kubrick and R.Lee)
Band of Brothers (technically not a movie, but had the same high production values)
Now, the worst war movie had to be the recent "Pearl Harbor" - wow - the Eric Mangini of war movies.
Thinking about it now, there really hasn't been a superb fight pilot movie. The Blue Max (w/George Peppard) was kind of close. Top Gun doesn't count - nor the scores of rip offs it spawned. Battle of Britain wasn't bad, but it was a bit too large in scope. Flight of the Intruder I guess is as close as you get recently.