As someone who doesn't hate everything about this game, but also sees it's flaws, I really have to say go with Fallout 4 unless you have a bunch of friends you can play with. Unless multiplayer is a priority, absolutely go with 4, especially since it's the cheaper option.

I do not because it's a lazy copy paste from Fallout 4 without NPCs, coherent story, and with more grinding. Lots of bugs, unpolished mess. This game is not even at top 10 of Steam's best selling games. And it suits it right. Users must vote with their wallets against these quick and lazy cashgrabs. It's one of few times when users are doing a right thing for drowning this game on its release. Stop being corporative cocksuckers. You are killing traditional gaming we knew and loved.

Withot stories and NPCs is just removing 80% of the original game and selling it at full price the parts that we had hated in the previous F4 game. How this shit can be even remotely redeemable in your eyes is beyound me.

EDIT: OMG they haven't even launched it on Steam. They know their game is a pile of horseshit.