I disagree that it is clear cut. I am currently playing through New Vegas on Steam Deck after falling off after multiple failed starts on 360. The biggest thing I love about Fallout 3 is the feeling of freedom. It genuinely feels like I can go wherever the hell I want and do whatever I want. Fallout 3 is maybe the only game where I have ever had a fantastic time playing a
black hat run. Fucking over Megaton gets you the Tenpenny apartment that makes your base of operations a different location, changing your trajectory and order of tackling quests. But I always felt free to be whoever and go/do whatever. Not pure evil, but fuck you I am going to do what I want in the moment.
New Vegas pissed me off to no end because it very much does not want you to do whatever you want. It wants you to go down a very specific route. You start in the center west. Try going north, Deathclaws. Try going east, giant scorpions. You are pretty much forced to go south. Because fuck you, this is the path. The game heavily nudges you to help the NCR, not even giving you a chance to fuck with Caesar until hours and hours later when you have likely been helping the NCR since forever. And if you decided to help the powder gangers early on over the NCR, because fuck the NCR they are liberal slavers who say "actually they are prisoners" then suddenly the NCR is pissed at you and you have no real alternative. It is either you work with them or fuck you. Having played through a big chunk twice before dropping it, I finally let myself engage on the game's terms and there is a lot of fun to be had. But I feel like I am fighting against the handholding constantly in a way I never did in Fallout 3.