specific niche forums foster good communities IMO. I've been on a rocketry forum for about 4 years and it's a very close knit healthy community. There's a forum called "the watering hole" for general off-topic discussion, i'm not there often but it looks to be a good place.

It also helps that the only ads/monetization going on are some banner ads from various rocketry store websites. The forum is run just as a service to the hobby and not to make money.