I'd say Fallout 4 simply because what it aims to do, it does very well even if its limited. They understand what the team can do, focused on that and delivered a solid experience. The marketing was done very well, no yeaaaaars of hype, just here is a trailer, see you in 6 months lol
Fallout 4 basically only promises to be a Fallout experience with exploring post-apocalyptic wilderness.
I enjoy how the VAC system is used and I believe the perk system is superior to any of the incremental upgrades that you do in cyberpunk outside of maybe the double jump and the mantis arms.
I believe what sets them apart even further is going to be the settlement system and how factions worked because throughout the game the decisions you made depending on what faction you sided with actually had big significant things happening to you in the game. Looking back at Fallout 4 now, I might like it less than New Vegas or Fallout 3 but looking at how things turned out for cyberpunk 2077, Fallout 4 is simply the far superior game in many many regards. They didn't bite off more than they could chew and the experience you are looking for was very much intact even if it wasn't as good as Fallout 3 or New Vegas in my personal opinion.
I feel cyberpunk 2077 kind of suffers from being a jack of all trades master of none as you end up getting an experience that you're not even quite sure in what area it's going to be the best in because I can't even really tell you that's an RPG it would be like saying Far Cry is an RPG or something, even Fallout 4 is criticisms for being less of an RPG compared to Fallout 3 and New Vegas seem pretty minute in comparison now in hindsight.
So Fallout 4 does a very good job at making all the things the factions do actually matter in the world.