I may well have/probably mentioned this before, but one of my greatest is people who ride bicycles on the sidewalk.
This happened to me again this morning, on my way to work. This isn't just annoying. This is dangerous to pedestrians because bicycles can move so quickly and quietly. It's a tragedy when a cyclist is killed in an accident with a motor vehicle, but the cycling community will get more support from me when cyclists stop riding on the sidewalk.
I could also add, Bicyclists who ride the wrong way on a one-way street. I once came within a foot of being run down by a cyclist (a food delivery person to judge from the container on the back of the bike) who was riding east on a street that's one-way west, and it was night, and he had no headlight on the bike.
My city is in the process of expanding and reordering bike lanes in the streets. The city will be moving the lane on my street (runs one-way west) from the north side to the south side of the street. This means we will be losing the loading zone in front of my building, which is located on the south side of the street. Once the move is complete, people in my building who will need to unload groceries, etc., from their cars will now have to do so on the north side of the street and then carry their groceries, etc., across the street to reach the building. And this is not a quiet residential street; this is a busy city street.