Maybe not the most useless.....I've always thought the UN troops should wear a fez for that very reason....
The fez at least makes you look taller. The traditional berets (of Spain, France, etc) were wide-brimmed. While the .mil beret is more svelte than those, it only serves as a minor head-warmer/sunburn protector for the scalp. The piss-cutter (don't know the proper name) was similarly useless.
This should be the issue hat: