I'm a very big fan of WWII movies made during WWII:
1. "The Purple Heart" (Dana Andrews, Richard Conti, Farley Granger). (The all-time champ!)
2. "Wake Island" (William Bendix).
3. "Gung Ho" (Randolph Scott).
After that:
4. "Sgt. York"
5. "From Here to Eternity"
6. "Apocalypse Now" (and "Redux").
7. "Paths of Glory"
8. "The Execution of Pvt. Slovik" (Martin Sheen's finest performance)
9. "The Caine Mutiny"
10. "Tora, Tora, Tora" (still the best Pearl Harbor film)