Between the two fallout games, I would have to go with new Vegas. With fallout 3 you have to wait thought a boring first 30 mins of story line crap and most of the game is a maze of abandoned buildings and tunnels to go from place to place. New Vegas puts you straight into the action and is a lot easier to get around. Not to mention all Round better game play.
Sims aha because really you can do what you want when you want and like New Vegas is more of a system game in my own opinion