Both are great, but Dyson is my favourite factory game out there. Absolutely beautiful game, and seems like a natural progression of a lot of what Factorio set out to do. Combat still isn’t implemented but honestly I am not that excited for it, I rarely play these games for the tower defense/combat aspects. If you like scaling up a factory to massive heights, DSP is a great game for you. If you just want to push to the victory condition with a more modest factory, that is still possible.

Satisfactory is a lot of fun, but I am waiting for the full story release to go back to it. The static world and hard-drive hunting makes me less keen to spin up a new playthrough, though I am aware Update 8 lets you skip the hard-drives if you see fit. I actually haven’t reached the proper satisfactory endgame like I did in factorio or DSP, I will admit. If you really like decorating and making things look aesthetic/clean/like a real factory, Satisfactory might appeal to you more. Has a lot of purely decorative things you can build, whereas DSP is basically all functional.

Satisfactory has their full story/release coming at some point, and DSP has their big combat update coming, so they both have major content that has yet to be released. If either of those things really appeal to you, might be worth waiting on their respective game.