Tera - Was enjoyable, though my PC could barely handle it so eventually I stopped playing it. Was good for live action MMO, minus poor PC. T_T
FFXIV - Played for almost year, actually has a better storyline past their earlier online FF game which sucked in story and gameplay. FFXIV had more engaging battle which was entertaining, plus the job switching with one character and mixing of abilities left it with a lingering 'Tactics' feel to it. Unfortunately, had to drop it since I don't have much time to do online gaming and really don't want to waste money on subscription when I barely play it.
Looking forward to The Division and H1Z1, waiting on both of those to drop on console.
Oh and though it isn't technically an MMO, Project Zomboid is pretty good as well. If you can locate a proper server for playtime. It is still an in development game, but despite it's sprite-ish graphics, it is a fun over the head zombie survival game. Cheap as well and pretty 'realistic,' given you have to eat and drink, plus you can get sick from heat/cold and eventually power will go out and water, forcing you to scavenge. Though servers for online play are issue on that regard, I found few fresh servers, most I drop in everything was already looted. v.v It does have singleplayer feature, but that is half the fun.