A Reddit user recently listed four reasons explaining why they prefer Fallout 3 over Fallout: New Vegas. They acknowledged that the latter offers richer content, branching paths, factions, and dialogue, but felt that Fallout 3 better matched their preferences in terms of exploration experience, protagonist development, and overall atmosphere.
The first reason is the subway system in the ruins of Washington. The urban areas in Fallout 3 consist of several isolated sections, with the subway serving both to connect these areas and as an independent underground exploration space. The dim tunnels and ghouls lurking in the darkness left a deep impression on some players, with some even considering it one of the most terrifying scenes in the entire series.
The second reason relates to the protagonist's background. Vault 101 showcases the protagonist's childhood experiences and provides a clear motivation for leaving the vault through their father, voiced by Liam Neeson. In contrast, the Courier in Fallout: New Vegas starts off by being shot, offering players less personal background information initially.
The third reason is the difference in early-game exploration between the two titles. This player believes that in Fallout: New Vegas, the route from Goodsprings to Primm is the most straightforward, while other directions are more restricted. Fallout 3, however, directs players toward Megaton after leaving the vault but also allows them to immediately explore other areas.
The fourth reason is the post-apocalyptic atmosphere. In Fallout: New Vegas, Las Vegas was preserved thanks to Mr. House's anti-missile system, so players face a functioning resort city with neon lights, surrounded by open desert. In contrast, the Capital Wasteland in Fallout 3 is littered with damaged bus stops and twisted trains, with the crumbling Washington Monument visible in the distance.
The discussion did not deny Fallout: New Vegas's advantages in branching content and character dialogue, but instead focused on comparing the different experiences offered by the two games. For this player, subway exploration, more concrete protagonist motivations, greater initial freedom of direction, and the desolate scenery of the Capital Wasteland were the main reasons for choosing Fallout 3 again.