From what I gather, the general consensus is that Doom Eternal is the better of the two most current (at this time) Doom games. That opinion is fairly consistent from reviews and posts I've read.

Doom Eternal is a go-go-go-go-go never stop moving always be shooting kind of game, as far as I can tell. IIRC there are even in-game hints that pretty much say "don't sit still". I'm just a super casual occasional gamer, so the always under attack game play in Eternal is a bit much while I'm also grappling with learning the controls since I don't really play first person shooters.

So for that reason, Doom is currently a better fit for me and my preferences. The game play is broken up into exploration that's punctuated with enemy encounters. And the encounters are largely set-up so that I can take on enemies at my own pace. Slower, more calculated, gives me time to think things through and consider strategy.

Also for some reason, the gyroscopic aiming wasn't enabled by default on the Steam Deck when I tried Doom Eternal. There are some settings I can adjust that are supposed to enable it, but I haven't spent much time testing those out. If I can make those work for me, then I suspect I'll have a much better experience with Eternal than I've had thus far.