My list..
1. Distracted drivers of any vehicle. The ones you can tell are on a cellphone/doing makeup/trimming beard while driving.
2. Taxi's. My worst run in with one was when he left-turned in front of me, thinking that by just flashing his high-beams I would slow down and let him go through with him not realizing/caring that I can't slow down as fast as a car.
But my biggest beef on the road...other idiots on motorcycles. Happened just last night. Was in line on the lakeshore just by the ACC to get onto the gardiner on-ramp. Everyone's behaving themselves, and along comes some a**hat in a cruiser, who decided he could ride along the lakeshore and dip into the on-ramp lane at the last minute. So now he's ****** off all the cagers and I'm 2 cars behind, surrounded by a bunch of angry drivers who are ****** off at bikers in general. So thanks buddy.