Starfield despite Fallout 4 being more conventional and "solid" when it comes to the Bethesda formula.
Fallout 4 is just a complete shitshow, when it comes to writing, to the factions, nothing made sense. Dialogs were insufferable (played it in french and you character always sounded like a buffoon), it was ridden with random outposts, there was only like 2 real cities (and only one that's interesting visually)...it's not a bad game but i remember hating it at launch. Just the look of the NPCs in this game i can't, and it might sound weird when the NPCs in Starfield took so much crap but compared to F4 i kinda like them.
The map and atmosphere were still great though, it was probably more coherent as a game. And there were some moments, very rare moments like with the ship with the robots, the first time you saw the airship of the Brotherhood, the radioactive area, some things like that that worked well.
Starfield is the Bethesda formula falling apart, whereas Fallout 4 was the Fallout franchise falling apart.
But if i have to chose i think Starfield is a stronger, more impactful game. Bethesda created an original world that they wanted to create, explored themes they wanted to explore for a long time (and that we had already seen glimpse of in their Fallout games) and i felt some authenticity in the game. The worldbuilding on that scale is really something even if it has a lot of shortcomings. Even if up close the locations are not very impressive technically and not very realistic i think it works, if we put aside the boring planets, i just had more fun exploring the handcrafted locations in Starfield than the entirety of Fallout 4.