Prior to DOOM 2016, the king for me has always been Half-Life 2 (though I'm still going back and forth whether this new Doom has finally topped it for me). The first Half-Life was pretty spectacular itself with its commitment to the first person perspective and the design of Black Mesa, while Episode 2 had some pretty great moments in a slightly more compact campaign. But everything about Half-Life 2, the journey you go on in that game, stands out so strongly for me.
You travel such a large distance and in such a variety of ways while still engaging in the core activity of shooting enemies. From zipping through the canals on the air boat, to the abandoned Ravenholm that still leaves me scarred with a fear of poison headcrabs, to the entirety of Highway 17 giving me the feeling of being on a virtual post apocalyptic road trip, to going above and below various parts of a war torn City 17, the various locales all stand out. Any moment in the game that would be seen as padding or downtime in any other campaign elevated the whole experience for me in service of keeping you in the character from start to finish, and not breaking you from the first person perspective. It's what made the first Half-Life work so well, and the same also goes for System Shock.
DOOM is only making me reconsider which game is better despite it being for different reasons. HL2 is like one big immersive experience with solid shooting fundamentals and level design while DOOM is like the closest FPS equivalent to a character action game. It's skill based, enemies are diverse and challenging, weapons are powerful, and the upgrade systems don't overshadow or compensate the need to play well in this game, but rather add more cool shit to do. It's so gameplay heavy in a way that makes me want to go through the campaign over and over, trying new stuff during combat arenas and see how good I can keep juking projectiles and not get hit.
So yeah, I'm just gonna put both as the best, because god dammit I hate having to choose between two fantastic things.