Singed
Singed is literally cancer, every game he just split pushes or proxies for free. If your team is even a little behind you just can't deal with him. You are FORCED to have a champion in his lane to keep from getting pushed to your nexus. It isn't fun. Even when you're beating him he isn't fun to play against. If you are behind you WILL lose, If you are ahead the singed is a useless liability to the team. There isn't any rewarding counterplay to be had from beating some stupid minion killing champ.
Singed players may as well just play games completely alone and kill minions all day.