Fallout 3, please, ANY DAY! (F3 = Fallout 3/FNV = Fallout New Vegas)
Anybody who says FNV is better than 3 hasn't properly played 3.
Yes, FNV might have better guns, but really, the story, nor the environment wowed me or made me as happy as F3 did. F3 wowed me, made me feel like I was apart of something big when I had first played. It has better atmosphere by far, making it feel like an actual post-apocalyptic world. New Vegas felt very un-like this to me, especially on The Strip. Yeah, it's powered by the Hoover Dam, but it drove me nuts how perfect and amazing it was. Actually, when I went there, it wasn't that amazing. I was expecting it to be some important, big, beautiful place, but it turned out to be small, full of loading screens, and only important for small parts of the main story-line.