Recently, I've tested a lot of MMOs, in order to create videos of the character creation processes (see my youtube channel). I've come to the following conclusion : most of them suck.
The ones that are "free to play" are free for a reason : Sadly, we are far from the "free as in open source" quality, they are closer to the free Facebook "games" from Zynga : The goal isn't that you have fun, it is to get you to buy virtual items.
Among all this suckiness, only a few MMOs deserve your time : World of Warcraft, the de facto standard, and Star Wars : The Old Republic, abbreviated as SWTOR.
In SWTOR, a lot of care went into crafting the various quests : Contrary to most, if not all other MMOs, the quest giver talks to you, explaining the mission.
This must have taken a lot of work, a lot of voice actors, and a lot of money. But it was worth it. Now, I cannot go back to a game where quests are given as "display text N°x : kill y monsters of type z".
One thing is disappointing in SWTOR : the choice of playable races. You can pick the humans, the cyborgs-humans, the blue humans, the red humans, or the green humans. I'm joking. No I'm not.
With the latest big patch (link to patch notes), a bunch of content was added to SWTOR, most notably the "Legacy" system. Your characters on the same server now share a lineage, they can even have a last name, as soon as one of them finishes the first chapter of the main quest. This is a great addition, and really adds a sense of history to the game.
Do not hesitate, buy it now, digitally at swtor.com, or on amazon if you'd rather have a box (link below).