My favorites are Paths Of Glory and Full Metal Jacket. (Maybe Dr. Strangelove should be #1; it's nuclear war, after all. ) FMJ's soundtrack contains "Surfin' Bird" and "Paint It Black". Enough said!: Buy Full Metal Jacket. WARNING: chances are that you won't like it, if you don't like war.
Patton is alright. George C. Scott is a genius (he was in Dr. Strangelove). He's a sore Oscar winner, though. But that's fine.
Apocalypse Now is, sometimes, visually striking; an "opera"; but it's a bit puffed up, IMHO (even for an "opera" - yeah: I hate operas that last ten hours). I prefer Platoon, if only because it's more plausible (being a personal work from the filmmaker). And maybe The Deer Hunter isn't the most accurate representation of war (especially for the Vietnamese), but, it does have some terrific performances.
The Thin Red Line is extraordinarily well made. Honestly, it is possibly the best anti-war film I've ever seen. A bit long, perhaps, but, unlike Apocalypse, it deals not with the chaos of war but with the ability of men to appreciate the beauty of life, despite the war. (That's a tough thing to put on the screen.) If I were a pothead, I'd love it more than I do now.
I've a soft spot for Coming Home (not a war movie really, but a very well acted soap opera). Mainly beacuse it allowed me to listen "Out Of Time" for the first time.
Godard's Les Carabiniers is fine for its cynicism. When it opened, it was blasted for its deliberate ugliness. (One critic derided the use of real stock footage of war, within the "fiction". But that was the point: Godard would insert the image of a dead soldier, without emphasizing it, letting the footage speak for itself.) Plus, it's short and does not evade humor. Bergman's Shame, on the other hand, is suffocating and humorless. And, in that way, it's a success.
I haven't watched Come And See (from Russia) yet; apparently, one of the most disturbing war movies ever made; more so, since it's captured from the view of a child. (It's in youtube, pero en español.)
Saving Private Ryan has some very good special effects. And that was it.