I enjoy Fallout 3 over New Vegas; post-apocalyptic DC grabbed me more than the Mojave, and it doesn't have nearly as much horrendous backtracking through the same areas that New Vegas does (through the stip, everywhere else is fine). Sure, the plot is more open-ended in NV, but they're both pretty average anyway. I play those games for the attachment to the characters themselves and the world they interact in, and Fallout 3 is more enjoyable for that.