The map isn't nearly as good in New Vegas, one central city type thing and everything else seems to revolve around it. Fallout 3, however, you have the main DC Ruins, the outskirts, Rivet City etc and the fact that the main parts are separated by water makes it a lot better again. The story is also better in Fallout 3 imo, more of a sense of importance. The general atmosphere in Fallout 3 make it a far superior game, it feels like you have places to go, whereas NV you feel like you have nowhere to go... The only thing I like more about NV compared to F3 is the fact that you can mod weapons.