Well I can only go from personal experience so...
I'm not too sure really, but I guess it really depends on how you define "worst". Imo, TF2 SPUF (steam powered users' forums) may be more active and have higher quality discussions, however, there's a lot more trolling and posting memes and such, and that's what half of the discussion is about. I don't really know how to describe the community. You can find some really good posts but the rest, like I said, seem immature. I mean there has been threads targeted at certain individuals just to make fun of them...And if I see another...SOLDIER UPDATE CONFIRMED!... 6_9 I know that reddit really isn't a forum, but r/tf2 might be less organized and some people might think it's just about posting pics, but the discussions seem to have less trolling and more legitimate answers. Imo, the reddit community is a lot friendlier. For example, I going to post a personal topic/question on r/tf2 that I would not dare to post on SPUF. The topic has been posted on r/tf2 some time ago from different people, and the answers all seem really friendly. I mean, like I said, SPUF seems a bit more trollish...but when I post there, I never go off topic! And I never troll at all! Yep, you'll see no overused memes and trade requests from me! No siree!
selling...Stout Shako for...2 refined!
I visit Bulbagarden sometimes. I've heard that they're more "strict" about certain stuff/rules? Not too sure really.