Bwuuuuuh...
Why ask such a difficult question? You know you're going to get near infinite votes for both games, and then quit counting.
Somehow, looking back, I think I did enjoy myself with oblivion, but for some reason I just can't get myself to think it's a good game. Morrowind, though I didn't play it that long, was awesome... Everything was just so... something.
I'm really enjoying DA:O at the moment, so I vote for that, but probably only because it's the freshest experience for me, not having played Baldur's Gate. I do have NWN, but for some reason I never got any further than the jail in the first city. I guess I just lost track of what I was supposed to be looking for.