Keep : Zu online (it's fun and there's barely any grind)
Uninstall : Angels online (didn't like it)
Keep : Fantasy masters (original concept, good time waster)
Keep : Dream of mirror online (one of the greatest f2p IMO)
Uninstall : Grandchase (Once again, i didnt like it that much)
Uninstall : Sealonline (Chose between domo and seal, I would go with domo)
Keep : Ijji gunz (Nice time waster, fun game overall)

That's my opinon. =)