For DC
OAAW #81-83, 91, 112, 151 and 168. There are some semi keys - check OGP
G.I. Combat #44, #68, #87, #91 and #138 - some semi keys between those numbers.
Star Spangled War Stories #84-#90, #138-141, #151 - some semi keys between them.
Our Fighting Forces #45 and #123 - I am sure early OFF issues may be valuable.
All American Men of War #67, #89 and #94
Weird War Tales #1-12 (Joe Kubert, Neal Adams #8, Tony DeZuñiga, Howard Chaykin, Alex Toth and Sheldon Mayer -- of course, the most famous writer of all war comic books is Robert Kanigher. This title is tough to find in high grade.
For Marvel (Atlas), Charlton and Fawcett - not sure about other publishers
Of course -- Sgt. Fury and His Howling Commandos #1 - #10
Battle, Battlefield, Battleground and Battle Cry
I just started to collect them but I am still learning the new stuffs outside DC.