For me, it'd be... A large variety of MMORPGs. I'm not sure if this counts since, while there may be a large number of people that dislike a game, there's still a significantly large amount of people that do like it. Most specifically I absolutely love Ragnarok Online. I dislike a lot of the recent changes, but there is always going to be a place for it in my heart. And it is the only game I'm able to listen to music to without any honest detraction from the game itself. I haven't played in quite a few months, and I'm still trying to find a game that I can play while chilling to music. And there's even a ton of great music in the game itself, which is a great change of pace. I feel like I've said too much about this.
More recently, I loved FF13 and am currently playing 14 (the new MMO). Thirteen had some bad points, but it had a lot of things that I honestly enjoyed about it. As for 14, well, I got the collectors edition for $15 AND it doesn't have a monthly subscription. I'm willing to admit that 14 is pretty bad, but it has a few aspects that genuinely interest me. Lots of people tell me "Wow! You only paid $15 but it's still a terrible game!", but I've enjoyed that $15 more than some people have enjoyed a $50 game, and the game itself is still expanding and becoming more interesting. So yeah.