Dragon Age: Origins worked so incredibly well because while I found a lot of its choices black-and-white (oftentimes good is the first in the list, evil is the lowest; see Bethesda's Fallout, Elder Scrolls, Mass Effect), it didn't explicitely say whether or not it was good nor evil. It was just a choice that would affect the world. No morality bar, just your companions' different dispositions to social taboos and Ferelden (and beyond in Sten's case) politics. My companions' feelings rarely entered into what I felt were ultimately better ways of living in Ferelden, which probably says a bit about my own politics.
Of all the games that really got me thinking about moral choices, Fallout: New Vegas was what allowed me to view them through a critical lens. While karma exists and plays only the teensiest role, it pales in comparison to your standing with different factions, each with their own flaws and merits. I found that playing politics gives much more roleplay opportunities than being good or evil, and that the politics can differ game-by-game, world-by-world whereas you kinda know what end of the binary moral spectrum the game will allow. New Vegas' political problems barely escape the Strip, and yet that's far more interesting to me than deciding how to deal with the issue of national hydration in Fallout 3 in either a good or evil fashion.