Euh.....i don't know if good mmorpg can be free forever.
Anyway, some good ones that i know are : Lineage 2, Rose Online, Ragnarok and Dofus.
Dofus is a mmropg tactic playing, in the first view it may look bad, but in fact it's a good game
, and they're working on Dofus 2 : Wakfu
Ragnarok is a great rpg *-*, but 16$/month for an old game from 5-6 years ago, up to u