Fallout 3 had a better atmosphere than vegas IMO. The ruins of the city, subways tunnels to travel, the absoulte warzone that was anywhere infested by the mutants. It really built up a world that was hostile and ruined. I wish FO3 had the same level of faction depth as FONV.
I’d say they’re equal, but also two very different feelings.
FO3 feels so much like a world reclaiming itself. You have a scant few major settlements, most things are still pretty ramshackle, everything feels shoved together. There’s an air of violent change, and you’re one of the hands helping to guide it down this new path.
New Vegas felt lived in. Settlements felt more established, you had The Strip as this beacon in the night, and you had outsiders shoving in on top of them. Yes, still striking the feel of “violent change”, but it felt less “Bring order to chaos” and more “The King is dead. Long live the King”.
The oppressing feeling Fallout 3’s tunnels had was so great, you felt like everything could pop at your head at any moments.