Black Hawk Down is one of the best 'combat' films out there. It had two advisors who were involved in the battle and it had approval from the US Gov. to use military machinery.
It's based off a book by the same name that was widely considered to be wholly accurate, and he helped with the screenplay.
We Were Soldiers is another movie that is very accurate, but it falters in a few moments with some serious cheese. As a whole, it's still very well produced and takes great pains for accuracy. And Sam Elliot owns.
Black Hawk Down is my all-time favorite combat film (tough to say it's a war movie) because it's so to the point and doesn't delve into war cliche or jingoism. Plus the commentary track by the delta and ranger soldiers on the deluxe edition is worth the price of the dvd.
Paths of Glory is a great movie, especially considering the fact its half a century old. Dialogue gets kinda over the top, but still an amazing movie for its time and still highly enjoyable.