I tend to get buzzed more by the Harley riders, since I ride on fun roads. They'll coast 'til they get right up next to me, then gun it. The exhaust from straight pipes out of a V-twin is deafening.

Trucks are more noticeable because they're bigger and generally have huge mirrors.

I get buzzed more by big 4-door sedans driven by the older people on their way to a casino. They seem to hug the right shoulder anyway.

-- I guess it's anybody that has an inherent sense of arrogance about their car and their 'right' to take up the whole road where bicycles don't belong: Big trucks, fast sports cars (guilty), loud and/or fast motorcycles, 'riced' Hondas, 'land yacht' big cars, etc.

--- but, I've been buzzed by everybody, there's really no bias, it seems.

edit///after re-reading this post...I need more coffee. Sorry for the discombobulation.