Honestly, I've been chasing that MMO social high since 'World of Warcraft' classic, and what works now is so different. It's less about big raids and more about systems that encourage organic, persistent connections. 'Final Fantasy XIV' still dominates for structured socializing—the housing wards feel like actual neighborhoods where you recognize your neighbors, and the Grand Company system creates smaller faction-based communities within the server. But for pure immersion, I keep going back to 'Guild Wars 2'. The meta-event chains force huge swathes of the map to cooperate for half an hour straight; you end up chatting with the same folks every day at certain event timers. It builds a weird sense of shared shift-work camaraderie.
Lately though, I'm more interested in games where social interaction is the point, not a side effect. 'VRChat' is the obvious one, but outside of VR, 'Swords of Legends Online' has these fantastic player-hosted tea parties and music performances. You just stumble on a bard playing in the woods and a dozen people sitting around. That kind of emergent, pointless socializing feels more 'alive' to me than any guild hall.