I like them both. Although I admit, FO3's leveled enemies, and abundance of raiders made it very, very fun; and the fact that I liked that pretty much, if you could manage it, you could go there in FO3. In NV, however, there's invisible walls on every "illegitimate" rout. But NV has more weapons, more recognizable weapons (I'm looking at YOU, Combat Shotgun!), and not only better weapon animations, but single-bullet reload animations. Sure, they're buggy, but they're there. Especially since they have a pump-action, weapon mods, and iron-sights. I have no problem with not iron sights, but when that means I can't sharp shoot unless I have Godly aim, or use VATS, there's a problem. Using iron sights not only makes me smile as the kind of person that enjoys aiming down the sights of a weapon, realistically, rather than slightly centering it to me, like my character's is afraid of the weapon; but it allows for sharpshooting, given you have the patience/time to wait for the loud end to be pointing at the enemy, rather than guessing; or just shooting and hitting a whole lot on non-living targets, like with the centered-aim method. I happen to like the whole Western theme, and the fact that there's now factions that actually have a major presence, and you can choose to side with. Although I'll admit Three Dog and the classics of GNR were a great companion, I loves me some cowboy tunes. I hate jazz more than I hate rap, though. And I hate rap more than "Your mom" or "Your face" "jokes". And that's a level of hatred I cannot explain, and wouldn't care to disclose if I could explain it.
As far as retro Fallout goes, though, that's way before my time. But, I haven't shunned these classic gems, however; I tried the Tactics demo not too long ago, and although I hate having the computer tell me I missed a shot I could have EASILY made in FPS mode; it's pretty fun. Generally, the only tactical RPG series I ever liked was the Disgaea series; another set of polished, yet under-appreciated gems. I'm thinking about trying to get me hands on the two original Fallouts, however. Let's hope they're as good as all of the Fallout nerds claim they are.