How about just caps? - One more reason why I like Fallout 3 better is because people in that game seemed unsettled.
New Vegas also has too many bugs (even after patch), and the different currency is crap. $NCR, Legion coins, and caps.
Or 'Hey! this subway crashed and blocked this entire tunnel.' 'This building collapsed and blocked the whole road.' When you see those things you don't even think about trying to get over them. In Fallout 3, it was very clear: Turn around, you can't go that way (map border). Why? Because I can't get to the top of a hill or a mountain. I know exactly where it is now, but the first time, I found Hidden Valley, Black Mountain, Helios One, and a bunch of radscorps and centaurs around scorpions gulch. In NV, I can walk across the map and not worry about shit. It's dark, it's confusing, and full of super mutants, raiders and ghouls. If I wanted to go into D.C., I would be afraid to.
Every time I replayed, I found something new (weapon, location, quest) and wanted to explore. I beat Fallout 3 one time, but restarted upwards of 12 times. Everytime I play I find myself missing fallout 3. I still play it just because it's fallout, my friends have it, and it's a new game.