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

Execution · Competitive PvP
High-speed tag-team execution and human prediction in gleeful early-Versus chaos.

Execution · Competitive PvP
Arc System Works' Persona spinoff fighter where summoned Personas double every character's offense.
Marvel vs. Capcom: Clash of Super Heroes leans Execution (Competitive PvP); Persona 4 Arena Ultimax leans Execution (Competitive PvP).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Marvel vs. Capcom: Clash of Super Heroes
Chain combos, assists and infinites demand fast precise hands
Persona 4 Arena Ultimax
Persona combos, one-more cancels, and tight confirms need real hands.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Marvel vs. Capcom: Clash of Super Heroes
Baiting a human's assist call or super is the duel
Persona 4 Arena Ultimax
Awakening threats and persona-break baits stay human guessing.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Marvel vs. Capcom: Clash of Super Heroes
Hidden characters aside, everything is public
Persona 4 Arena Ultimax
Deterministic; status effects are earned, not random.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Marvel vs. Capcom: Clash of Super Heroes
Team composition and infinite-combo knowledge define the meta
Persona 4 Arena Ultimax
Persona card management and burst routing are labbable.
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.