i'll not use word hate but dislike to prevent lichess from labeling this as hate thread and closing it.
mine:
who leave w/o resigning
i can't remember anything else rn.
EDIT: people who try scholar's mate
The players who defeat me. :]
Players who ignore the rematch request, but don't leave the post-game room. I'd rather they click decline if they aren't going to play again.
Of course the cheaters have to be first. The rage quits are close. Although there are a few in between, the very high rated players who ask, "I've been playing for two hours. Am I any good?".
cheaters and who don't quit game when losing letting time passes by.
Cheaters and people who brag about their wins
On iphone you can’t decline a rematch when you are not in the application.
Sometimes the cursor or touchscreen fails and I do a bad move, request to undo the move and reject it despite i explain them, or when I'm winning, but for a emergency I have to get out, and request to draw and nothing, specialy with a players lower rated wich are completely loss
Players who do scholar's mate
The ones who aren't polite in the chat. So what if you dropped a few rating points, it's just one game, there's no need to be rude.