It depends on preference

Like team battles? Try Guild Wars or other MMORPGs that focus around guild combat/team combat.

Like solo battles? Try some games that focus on 1v1 combat. It's as simple as that.

It all depends n prefernence.

Me? I like to play with teams, so I usually play Guild Wars and ZU Online.

Guild Wars is strictly PvP for me, and ZU Online is questing/leveling and then we have a guild area siege event for like 4 hours every day.

It's nice for me.