It's too difficult for me to make a "top 3"...
so I rather put here some films I liked most, in no particular order:
- Master & Commander
- Das Boot (in Italy it's known as "U-Boot 96", not sure about the english title)
- Letters from Iwo Jima
- All quiet on the western front (both versions, but I liked most the 1930 one)
and if you liked Stalingrad, you may have a look at "Italiani brava gente", an italian depiction of the eastern front. a bit outdated and a bit too rethoric but bears many similarities to "Stalingrad".