Everquest, the original.

Two guilds come to mind.

I was younger, too young to work, so one summer break I joined up with a European guild to raid with. Lots of fun, learned a but about British (primarily) culture. Lots of fun, even when I joined another guild I raided with them from time to time.

The other was a family guild. It eventually fell apart as the adults got busier with their careers and kids and shit. But the inner circle, so to speak, were invited to a bulletin board and we all talked for years after that. Eventually lost contact with them as I grew up and got busy with life.

Lots of fond memories, and a couple not so fond (RNG hates me, in every way). But they were along when RNG screwed me time and again, and were always willing to try again. Lots of love for those folks.