head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.

Execution · Pure Mechanics
Arcade brawler execution against fully memorisable enemy waves.

Execution · Pure Mechanics
Push-forward arena FPS where movement and aim are the whole game.
Alien vs. Predator leans Execution (Pure Mechanics); DOOM (2016) leans Execution (Pure Mechanics).
DOOM (2016) leans a little harder on execution, though the gap is small.
Alien vs. Predator
Crowd control, spacing and combo timing carry the arcade brawling
DOOM (2016)
Aim, movement, glory-kill timing all peak.
DOOM (2016) leans a little harder on reads, though the gap is small.
Alien vs. Predator
Xenomorph waves are scripted patterns, not minds
DOOM (2016)
Demons scripted attack patterns.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Alien vs. Predator
Enemy spawns are fixed and memorable
DOOM (2016)
Minimal encounter randomness.
DOOM (2016) leans a little harder on optimization, though the gap is small.
Alien vs. Predator
Learning spawn layouts and character tools maximises one-credit runs
DOOM (2016)
Rune and weapon mod picks meaningful.
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.