Personally I like Wings of War. Game play is fairly easy in the basic rules, and can be made more complex with the addition of AA guns, bombers and bombing, Drachens, Altitude, incendiary rounds, ace rules, and the like.
The WW2 rules are, for my money, not as clean. I also prefer the sort of continual chess of the WW1 vs the single pass annihilation from 20mm cannons in WW2.
The planes are done reasonably well, and the cards do an okay job showcasing the difference in plane capabilities.