Well, they’re all good.

The older ones defined the genre. They’re still fun to play albeit a little dated. No idea how good the Switch ports are.

Doom 3 is slower and more focused on horror than the others. It’s a good horror fps but not a good Doom game.

Doom 2016 is the first of the modern Doom games. Fast, brutal, super fun through and through. If in doubt start with that one.

Doom Eternal is the second of the modern Doom games. It’s even faster than 2016. But it has more focus on using every mechanic at your disposal. Learning those mechanics is a little bit tedious at first. But once everything is available it’s an adrenaline pumping high speed 4D chess. When you’ve mastered everything every fight lets you enter a trance of violence that’s absolute bliss.