They can all be annoying and terrible golf partners, but I voted for slow golfers.
Wannabe Pro - Whatever floats your boat. Annoying, but otherwise, just don't care.
Slow Golfer - This affects me and my round and a lot of other people's rounds. Unacceptable.
Vice Ridden - Annoying but otherwise not an issue.
Rage-a-holic - Embarrassing but I can still play my game. However, he may be eliminated from my "buddy list" for golfing if after asking him to to relax and the rage attacks continue. This is a close second to the slow golfer for me.
Cheater - Don't care what rules he plays by....Just no money games or other competitive rounds. Casual rounds only. I enjoy golfing (casual round) with a few guys who routinely fluff their lies, change to a different ball for putting, miraculously "find" lost balls, etc.
Distracter - I really don't distract easily. They can cough, hack, or whatever to their hearts content. The fact that I only have one functional ear probably helps here.