If you consider each system fundamentally different then Final Fantasy XIV now appears to have has 8 separate Quest types, with 2 coming soon. They all act differently, and were all released before a year had passed since release.
Mission Quests
Class Mission Quests
Guild Leves
Local Leves
Faction Leves
Behests
Side Quests
Guild Tasks
And soon we'll have:
Company Quests
Dungeon Quests
Am I counting wrong or missing something?