PC Gaming.
I get sick of the disgusting community that has developed on Steam. In my single year of having a good gaming PC, I got put through more harassment and abuse than I EVER got out of Xbox and Playstation. I mean, I bought a weapon for TF2 from the community market that had a decal on it that read "UR A FAGGOT". Most of the times I kill someone in TF2, I get immediate text chat hate telling me I'm bad or that I should go kill myself or some other shit. That's to say nothing of the other obnoxious shit on steam like troll tags, unfunny "joke" reviews, hacking in games, the hate in greenlight and many other problems it has.
It's not ALL bad, but I genuinely dislike playing multiplayer on my PC. I had a nice long honeymoon with it, but I've since drifted back to my Wii U and PS3 for their exclusives and superior online communities.
Then comes the "master race" garbage. Never before have I seen such a large group of people get so needlessly heated over something as stupid as how someone chooses to enjoy a hobby (excluding anime fans). Someone wants to play Borderlands on console? Go right ahead. I don't give a shit as long as they're enjoying themselves, so why are you idiots so worried about it?
Anime.
I'm a HUGE fan of Japanese culture. I have studied the language for 3 years, have made friends with natives, watch anime, collect figures, etc. But the community for anime and Japanese media as a whole is fucking TOXIC. Don't like Japanese voice acting but love Japanese media? Hope you're ready to have no one to talk to about it. I get sick of the constant sub vs dub bullshit (normally fought by people who have ZERO knowledge of Japanese), the obnoxious rabid fans, the "your favorite show is shit" mentality, the double standards about translations, the rampant justification for piracy, etc.
Super Smash Bros.
Go to a meetup to see why. Unfunny memes being yelled out, constant bickering over which game is best, and no one will play anything other than melee or PM with tourney rules. Like items? TOO BAD! Like 64 or Smash 4? TOO BAD, now you get to hear about why they're shit!