For me the worst are taxis - by far. They don't give a crap about anyone else, just do what they want to when they want to. Taxis have cut me off, pulled over right in front of me, passed me very, very close, etc. waaaay too many times. And they are the most likely to honk when I take lane and they can't pass me right away. I know they need to get from one place to another quickly, but I want to live.

Second on the list are male drivers, mainly youngish. If something passes me very close at high speed, it's typically small car (compact, maybe medium) with a young male driver in it.

Motorists I know here told me to watch out for buses, but I find bus drivers very patient and careful.