the best PvP ever in an MMO. it's because you need 3 factions to make great PvP,
Did you ever play Shadowbane? It was a Mac/PC simultaneous release back in 2003 and closed in 2009. It was pure PVP. Players built cities, sieged other player cities, etc. It was literally a game of thrones where the political landscape was 100% dictated by the players. It had a great lore for RP'ing and background story but no actual quests and you got xp both of monsters and players you killed.
It was totally a niche game, and Ubisoft did a horrible job managing it but it was the most fun I've ever had in an MMO. Nothing like 200 vs 200 people going at it for 3+ hours at a time.