Runescape is a reeaallly old game that is still pretty cool. It's been "refurbished" multiple times now that it is so different from how it was when first launched.
C9? I'll check it out. As far as EVE goes, EVE has TONS of fansites bit those fansites don't have forums. It's all databases, tools, resources, articles. Haven't seen many active EVE discussion forums besides the official forum.
I'm surprised nobody has mentioned Wildstar, Runes of Magic, or any other MMO. World of Warcraft and Guild Wars 2 are like the top 2 games in terms of guilds and communities, though Guild Wars 2 doesn't have many active fansites....it's got one fansite by Curse, but the rules are soooo strict. World of Warcraft has a few decent fansites.....it sucks that you can't post on their official forum though....only subscribers are allowed.
I actually conjured up a list of anime MMOs but although they fit the criteria of "really active and friendly", very few were active in terms of guild activity. I think Final Fantasy was the biggest anime MMO I've seen with guilds. Fiesta as well.
So....Tera, Rift, GW2, and WoW only? Do people still play Runescape?
EQ2 has great guild activity. Unfortunately the population is lacking due to it being an older game, but it going f2p has helped. There are guilds out there with many members that are active. Not to mention the guild halls! I don't believe guild feel very guildy without a guild hall. My guild's hall in EQ2 is just massive... just massive with everything and anything inside it. I get lost in there all the time.