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

Execution · Competitive PvP
The Wii U Smash that restored competitive pace and a huge roster of labbable kill confirms.
Marvel vs. Capcom: Clash of Super Heroes leans Execution (Competitive PvP); Super Smash Bros. for Wii U leans Execution (Competitive PvP).
Marvel vs. Capcom: Clash of Super Heroes leans a little harder on execution, though the gap is small.
Marvel vs. Capcom: Clash of Super Heroes
Chain combos, assists and infinites demand fast precise hands
Super Smash Bros. for Wii U
Perfect pivots and precise aerial spacing reward sharp 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
Super Smash Bros. for Wii U
Ledge-trap and landing-trap guessing against humans never converges.
Super Smash Bros. for Wii U leans a little harder on variance, though the gap is small.
Marvel vs. Capcom: Clash of Super Heroes
Hidden characters aside, everything is public
Super Smash Bros. for Wii U
Tripping removed; only minor move RNG remains.
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
Super Smash Bros. for Wii U
Rage mechanics and kill-confirm percents are deeply 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.