head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Optimization · Practiced Mastery
Crafting absurd weapons and routing a zombie-filled city against the clock.

Optimization · Practiced Mastery
Co-op superhero brawler about assembling the right four-hero squad and builds.
Dead Rising 3 leans Optimization (Practiced Mastery); Marvel: Ultimate Alliance leans Optimization (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Dead Rising 3
Crowd fighting takes modest aim and dodge timing
Marvel: Ultimate Alliance
brawling and dodge timing are forgiving
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Dead Rising 3
Zombies and psychopaths run fixed scripts, never adapt
Marvel: Ultimate Alliance
enemies are scripted mobs
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Dead Rising 3
Weapon and blueprint locations are unknown until explored
Marvel: Ultimate Alliance
some loot and unlock randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Dead Rising 3
Combo weapon crafting and timed routing drive efficient runs
Marvel: Ultimate Alliance
team bonuses, gear, and skill builds carry difficulty
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.