My boyfriend prefers 3 between the two though New Vegas has more stuff. New Vegas has more locations, but nothing much to them, so exploration can be pointless. Too bug as well. 3 had a better story to it compared to New Vegas.
I didn't play the games, but I watched him play it. I like watching 3 more than New Vegas because there was more action going on in the areas. Things weren't so spread out in 3 and when you got to an area, there was something to do event wise or to kill creature wise.
New Vegas to him and me, there seemed to be too many corners cut to just get it out.