I've been with MMOs starting about 2000 with EverQuest live, then played about 90% of most MMO titles through today. Some for years (CoH, EQ2, ESO...) and some for a short time (New World, Tabula Rasa, etc). All of them mostly (exception for Korean grinders like Lineage or Grenado Espada or some true flops like Matrix Online) had some sort of good community, large or small, if you looked, even Snorecraft.
City of Heroes was a real gem in live, and even moreso now after 'the snap'. Multiple factors, but the essence of the game is generally (despite the modern deconstruction) about achieving something better. On a cathartic level, CoH combat is really truly glorious, colorful, beautiful chaos, and zapping hords of Malta and shaking your fist in the face of various nefarious AVs is very satisfying when managing my stress. So is just walking through my base and having head-cannon tie-ins to storylines (like Dark Astoria). On the social level, this is a very helpful and generous community overall, and I've witnessed/experienced many acts of genuine kindness. That just rubs off.
Good second runner ups for community in my own experience have been Everquest 2, The Secret World, and Warhammer Online (faction-based community).
Anyway, you are great, I like zapping Hellions with you all. I guess that's why I'm here 19 years later.