Both Bethesda series are amazing in their own respect, And I've enjoyed wasting countless hours of fighting super mutants or slaying dragons. There are a few main reasons why I prefer Elder Scrolls:
1. Fantasy Setting.
I've always been a fan of fantasy setting since they don't take place in the real world. Whenever I want to play a game, Or read a book even, I love immersing myself in worlds that I could never visit myself, And Tamriel is no exception. From the ashy lands of Morrowind to the frozen wasteland that is Skyrim, And out next stop most likely leading us to Hammerfall or High Rock, I've found myself completely in awe of the landscape that I was exploring. While Fallout gives us a great visual of what a post-apocalyptic world may look like, I prefer seeing vibrant colours in the natural landscape.
2. The Lore
I love lore when it comes to video games, And the more lore a game provides, The more invested I become. Both Fallout and Elder Scrolls lores are amazing, Though Elder Scrolls does a much better job of providing lore within the games. Instead of having to rely on emails in Fallout, We get actual books in ES, And that just reads much more smoothly for me.
You can be an Argonian in ES. You can't be an Argonian in Fallout.
I've found the quests in ES to be more interesting than in Fallout. What other game can you get wasted in a bar, Get married, Steal a horse, And wake up with no memory and having to fix your drunken mistakes? In all serious, I loved exploring caves and the dwarven ruins (despite how much I verbally say I hate exploring dwarven ruins), And I just never got as much excitement with the quests in Fallout.