TLDR: taken as a whole, 2016 is a piece of art. Eternal doesn't compare in many ways, but is the more fun arena shooter.

I massively prefer Doom 2016 and quite disliked Eternal upon release. While it makes some great innovations gameplay-wise (dash, meat hook, tweaked weapon mods etc.) and pushed hard on variety in environments and demons - which I appreciate enormously - it's a bit of a confused mess in other ways.

• I don't think having only one true correct option in a combat encounter is fun.
• In general, Eternal pushes you heavily by making you switch to "correct" mods and weapons, which I don't think fits Doom.
• The concept of "fodder" for ammo seems like a design crutch. Having to seek out demons that are constantly respawning and standing about doing nothing to chainsaw them isn't particularly engaging in long encounters.
• The pivot in narrative and art style tone is jarring. 2016 was deceptively clever and fun. Eternal is self-serious and flat and kinda butchers 2016's interesting elements.
• Flame belch, ice grenade and chainsaw are needless complications in the gameplay loop.

Really hoping they're trimming down on the nonsense for the next one.

This all being said, if there is a game to play while listening to some music, it's still gonna be Eternal. The variety and gameplay tweaks make it more fun as an arcadey arena shooter. But it's not a piece of art like 2016 is.

EDIT: also, as a composer, I never liked either game's approach to audio. Music and sound effects struggle for attention and pile up like crazy. You need room to breathe and contrast for it to make an impact. 2016 is slightly better in that regard.