A good story.I don't care if it's linear or not, I don't care if I get to pick my morality or not. Both freedom and the lack of it have their advantages and disadvantages. I just want there to be interesting characters, a fun plot twist or two and a good setting to back it all up. I can even forgive a weak main plot if the other elements are good. For instance, Mass Effect 2 had a crappy main plot, but the setting was great, the characters were interesting and memorable and there were some nice twists to the various plots in the game.
A good choice of stats, skills, spells, items, builds, etc. Or to be more specific, meaningful choices. Quantity is welcome, but quality is what counts to me. I'd rather get to pick a handful of spells/powerups during the game and have each of them provide meaningful changes to my gameplay than spend thousands of arbitrary points on hundreds of levelups that only make my sword swing a bit harder. Nothing kills me inside like seeing "Your attacks do 1% more damage" or some such crap as a reward for leveling up.
I don't care if the world is open or not. Sandbox can be fun, but it also tends to mean a less structured narrative and a less focused experience. It's always a tradeoff. I don't care if I make my own character or use a predetermined one. Making your own tends to let you customize him more, but also makes him a blank slate, meaning that it's up to everyone else to be interesting. You'll always be a flat boring piece of bland. Again, tradeoffs.
In short, I want to have fun making my badarse character and guide him through some pretty scenery while surrounded by cool people.
