Wow, not sure if you are serious or not. Feels like a big troll topic (not that I am calling you a troll).
New Vegas was developed by people that worked on the original Fallouts. Fallout New Vegas is a Fallout game, it has that "real Fallout feel." Fallout 3 on the other hand does not.
New Vegas is closer to a true sequel to Fallout 2 than Fallout 3, which is only a sequel in name only. Fallout 3 is full of plot holes and piss poor writing and isn't much of an RPG, its so linear. Good vs Evil. Fallout 3 takes the main elements from Fallout and Fallout 2 and sticks them on the East Coast with no real thought, hence (some of ) the plot holes.