SWTOR: Play your game.
As most of you know, SWTOR features an alignment system to increase the story-telling potential. The dialogue wheel gives you different choices for how you respond in conversations, and sometime these choices will give you light or dark side points for choosing them.
These choices also have the potential to change your gameplay. For instance in the first imperial flashpoint, choosing to let a certain person live will have different bosses and gameplay than if you had chosen to kill him.
NPCs will respond to you diffrently based upon your choices. New stories will unfold based upon your actions. Perhaps you killed someone earlier in the game. You may see their relatives or friends come to exact revenge on you later on. Or maybe you chose to save someone in order to choose the lightside option during your travels. it could actually turn out that due to you letting this person live, they have now developed and tested a weapon that wipes out entire civilizations.
Another often overlooked aspect of this is character selection. A person recently said to me that they don't want to roll any Republic characters because they usually play the "good" faction in games, and don't care for the whole goody goody thing with the Republic.
This is why TOR is so great.
You don't need to play the predetermined archtype. You can play as you see fit.
Play as a selfish money grubbing Smuggler who only cares about himself.
Be a Trooper that has no morality, and instead enjoys suffereing of others to further his career.
Act out your fantasy of a Jedi Knight or Consular who defies the Jedi council's peaceful wishes, and instead goes about with a dominant hand crushing those that don't live up to a personal code.
Be a Bounty Hunter that cares more about people than money.
Play as an Imperial Agent who gets his job done, but never at the expense of killing innocents.
Become a Sith who doesn't believe in torture and puts the well being of the people above that of the ideology of the Emperor.
Play this game the way you want to play it.