from the 3 games you named. i would say iris online or atlantica. war of angels is right there with rappelz.
iris online has a pretty fun pvp event that goes on, and you can get in it no matter what your lvl is.
They also got rid of the different nation part of the game, so your just randomly huddled in a red team or a blue team.
pretty fun, but gets bored fast. I spend more time looking at screenshots of other people playing games on onrpg.com then i do playing games so.. meh :<
atlantica becomes cash shop dependent as you start climbin up on the lvls.