Sonic and Call of Duty are up there, but if I had to choose one, Sonic.
That game's fanbase is just horrible, with people doing weird things, like terrible drawings of OCs and comics on DeviantArt, and other disturbing things I really don't wanna get into.
"Just for comparison Uncharted 4 was 20x bigger than Splatoon 2. This shows the huge difference between Sony's first-party games and Nintendo's first-party games."