I liked Fallout 3 better. Maybe it is because I spent 40 + hours in that game and only 25 hours on New Vegas. Also I can't finish the latter because a glitch (or at lesat I think it is a glitch) ocurred making it imposible to finish the game. I have a forum thread discussing that. Also I think Fallout 3 was "scarier", I shit my pants every time a Feral Ghoul SNeaks up behind me while travelling through the metro stations. But you have to give some credit to New Vegas, some things were much better in that game, especially the companion system.
Also a really good MMORPG I used to play is Regnum Online. There are 3 kingdoms and they fight with each other and stuff. These kingodms correspond to elemts of nature. The only bad thing I can say about it (if you do nnot speak spanish that is) is that it is in Spanish. Not a problem for me beacuse I am from Argentina. But I think there is an English version that was realeased no too long ago.