Surveys is meh, it's dead for the most part. I love OT and FG though. I've met some dope people and had some wonderful conversations. OT and FG is like a community inside of a community.
G&R can be alright if people post some thought-provoking questions, like abraker's hitsound thread not too long ago. General Discussion is similar, but there's not much new content over there.
Otaku Culture, Music Hall, and Video Games are all in the same vein of "occasionally talking about specific interests."
did I forget to mention MAFIA??? It'd be super cool if it wasn't dead, so come join us!
https://osu.ppy.sh/forum/p/6942722