I'd have to say that in terms of the sake of the vision, Fallout 3 was far superior as a standalone title than Fallout: New Vegas was.
Fallout 3 had a plot where you had a father who was intrinsic to your story, and, while many people didn't like that, it's important to realize that any character you play as will have parents, and having them be visually represented in your game is not necessarily a bad thing. To be honest, the "Dad" in FO3 could have been "Dr. Joe" instead, and players would think he was great (or perhaps more fitting/better)
Environment-wise, F0:NV was terrible. The representation of New Vegas in the initial trailers left me thinking this was a vast, surviving, somewhat thriving community where the lights of teh city were something that contrasted with the emptiness around it. However, the New Vegas in the game had roughly 6 buildings to enter on the most important part of the city, and everywhere else was easily overlooked if you weren't focused on going there on your own. The desert, the actual desert, felt more abundant in life than Fallout 3 did. With growing plants and greenery in many different locations, with plants and consumables everywhere, it was hard to think that we were in a desert, and not just a particularly dry field of yellow dirt (one think I have to be petty about was how the 'sand' of New Vegas looked almost like banana pudding dripped over mountains). The sky was filled with clouds, it was very 'full' of locations, and you ended up exploring about 70% of the map by the time you even met Mr. House. Fallout 3, on the other hand, was quite more atmospheric. With broken ruined trees, no signs of plant life beyond brown-crusty looking bushes and cruddy dressers and wardrobes haphazardly discarded in the Capitol Wasteland, there was little sign of life, with purified water being more valuable than gold, there's a sense of 'realness' involved with the desolate landscape, that pure water is hard to come by, and it's needed by beggars who sound as though they are on their last legs, incredibly grateful that you'll give them water, and almost crying when you don't. With a pale green hue over the nearly empty skies, the sun leaving a sickly pink horizon line, with large mountains in the distance, you truly feel that this is a wasteland, even BEFORE you see the city so ruined that the subway tunnels are the easiest accessible routes, if you can navigate your way through them.
In terms of guns and ammo, I've got to give it to New Vegas, they did a real good job with that one. While Fallout 3 had all the important elements covered by the weapons spectrum, New Vegas jumped it by a long shot. With far more weapons, weapon customization, you became emotionally attached to the weapon, the time and caps you spent keeping it in good condition made it your own, and although there were many like it, it was yours. The different kinds of ammunition made the game more interesting as well. With armor piercing rounds making fighting what few robots were in New Vegas easier, as well as the inevitable scrambling to kill a charging Deathclaw that much easier. Fallout 3 didn't have those moments, and the fact that some enemies like Super Mutant Overlords did a guaranteed 40 damage to you BEFORE the damage from their tri-beam laser rifle was calcualted, makes New Vegas the clear winner in that respect.
In terms of actual SURVIVAL, this being a wasteland survival genre, Fallout 3 takes the prize there. With cheap, inefficient weapons, you were pressured to save every bullet, to take as few shots as you could, and even when you were in the mid-game, exploration was key to setting up a good armory, with vendors selling scrips and scraps of various itedm you could use to make your own weapons with, or maybe some 24 rounds for your Chinese Officer's Pistol, it was caps well spent (usually). New Vegas has a thriving economy, and it shows. With the cap for the Winterized T51-b armor from the Operation: Anchorage add-on usuall hitting the cap limit of 999, New Vegas laughs at that and gives you a Marksman Carbine for 5499 caps, which you eagerly throw away, since even pretending to save has netted me almost 200,000+ caps, 5 gold bars from the Sierra Madre, and large amounts of NCR dollars and Legion Denari(i?)(us's?). The economy was something that did not make the game feel like survival, in so much as an adventure. For an RPG, that's not bad, but for a wasteland survival RPG, that's not hitting the right mark.
While New Vegas has factions, it feels to organized, with the only real raider band being the Fiends, and the only other pseudo-bandit faction being the Great Khans, The story drove all the main faction choices, with so much that could be done with the factions (another entire monologue there), the world felt a lot smaller than Fallout 3, with bandits camping on a ruined overpass, using destroyed cars as cover as they took potshots at you with Hunting Rifles, and you're low on stimpacs. That's a more "wasteland survival" experience than running into prisoners who drop like flies FIGHTING flies (not cazadores, whole other experience there). Now, I've only played the console versions, so I've seen the base game, unedited, and unchanged apart from add-ons, and DLC's, so mods aside, I'll stay with Fallout 3, it was hard, tough, and challenging. It felt desolate, ruined, and there was enough in that seemingly empty wasteland that I felt like I was truly alone, working only at my whims to help or to hinder those around me.