Most MMOs provide you with the basics: instances, player housing, an in-game economy, and so on. What the vast majority of MMOs don't do is provide you with elaborate systems of political intrigue (outside of the very few and the proud, like EVE and Dark Age of Camelot -- where my Dark Age fans at?).
TERA is the newest game to throw it's hat in the ring, as it is all set to introduce the Vanarch Election system, which will allow you to actually campaign and vote for your favorite potential official. Elected officials which will have some say on how the game's zones are designed, and you'll be able to campaign just like a real life politician, as well as provide a platform on how you would change the world's inner-workings.
Elected officials will have the ability to hire certain vendor NPCs, as well as the power to declare some zones "peace zones" or "PVP (warring) zones". If you win the election, you'll have the ability to set taxes on items, and gain special official only mounts. In order to qualify, you have to have a max level character (60), be the leader of a Level 3 Guild, and pony up a 3000 gold submission fee and 100 Guild Feats of Strength (to prove that you know what you're doing).
I'm currently level 30 in TERA, and overall it's been a pretty wonderful experience. I play entirely with an Xbox 360 controller, and it honestly feels like I'm playing an action game on par with some of the best on the market.
Although there are plenty of quests (meaning there's very to little raw mob grinding), it is a typical MMO in that the quests themselves don't typically break the mold of your average online RPG. Where the game really shines is grouped combat with world map BAMs (Big Ass Monsters; essentially what other MMos call "World Bosses") and in Dungeons/Instances.
To give you a bit of background on how combat works, Warriors, which basically play like Rogues in other titles, can flip back and forth in real-time to dodge attacks and gain a backstabbing vantage point on enemy BAMs. Berserkers have a block ability that mitigates damage, and requires precise timing. It's essentially Vindictus in a true open world MMO setting.
Each class feels fairly unique in their role, and TERA's dungeon finder (take notes TOR) helps you find a group fairly quickly, meaning there is hardly any lost/wasted time. As someone who has ran around in Orgrimmar for hours at a time looking for groups before WoW's dungeon finder, I can appreciate the love.
As long as you're ok with some tried and true MMO conventions, TERA can be a really nice way to spend your time online.
Vanarch Election Calendar [TERA]