Phoenix dynasty.It's very fun for me to the point where the grinding is ignored.You hardly have to kill anything because you do a lot more questing than griding.The grind for me is minimal because I only gained 2 levels from grinding.But the quests is where I got most of my levels.Plus you have the x2 experience at your disposal.It's not an event but a permanent part of the game.

Level 15 btw.