If you were in charge of picking the airplanes that your country would have during a WWII-type war -- what 5 aircraft would you pick?  Assume that the aircraft perform just as they do in Aces High, that you can pick any non-perk plane from Aces High, and that cost is not a factor.  (These are what you'd pick for a real war, not just what you like flying best in the Main Arena.)
I'd go for the following:
P-47N.  For fighter, fighter-bomber, and high-altitude escort.  I'd pick this because of its range, speed, performance at altitude, lethality, ruggedness, and ability to carry a lot of ordnance.  The P-51D is also a contender here for me, but the P-47N is more rugged and has more punch.
F4U-1D.  For my carrier aircraft, both as fighter and divebomber; also as general fighter and fighter-bomber.  It's faster than the F6F, outturns the F6F by a little, and carries more than the F6F in Aces High.
B-24J.  For my heavy bomber.  The Lancaster is a great plane, but its defense armament isn't nearly as good as the B-24 and B-17.  I'd pick the B-24 over the B-17 because the B-24 is a little faster and carries a bit more, yet has the same good defensive armament.
B-25H.  With cannon, for ground attack and attack against ground vehicles.  The cannon is a great weapon against ground vehicles and buildings.  I'd pick it over the Il-2 as it carries more bombs and especially because of the cannon.
Spitfire Mk XVI.  For quick-climbing field defense and intercept.  This would be a base-defense fighter and a fighter to use when you need to get up in a hurry to intercept things.