PvP.

In fact, I like FF14's PvP system overal, and do participate in in occasionally when I feel like this. It's just that I simply don't like PvP overal no matter what game it is, and that's why that's the least favorite activity and also why I appreciate FF14 for being PvE focused game without openworld PvP.

Outside of this... probably Pagos during its release days. It was painful.