/b/ - normie tier.
/v/ - mostly children or adults who act like children
/r9k/ - mostly mentally ill women haters
/pol/ - trump dick sucking, no discourse, no fun.
/soc/ - attention whores.
/x/ - used to have fun original content but now is infested by actual crazy people.
/mu/ - pretentious faggots that never actually discuss music.
/mlp/ - do I even need to explain
/diy/ - mostly respectful community of productive people
/po/ - papercraft is a fun hobby and the people are chill.
/bant/ - basically /b/ but the normies haven't found it yet
/s4s/ - can get old if you visit too often, but absurdist humor is funny in small doses.
/adv/ - decent threads sometimes, lots of shitposting though
/his/ - when actual history discussions aren't derailed by Nazi Larpers it can be interesting.
/int/ - same as /his/
These are just the ones that stick out in my head.