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 · Grand Arena
Chaotic tag fighter whose top tiers reward blistering execution and assist mastery.

Execution · Grand Arena
A tag-team crossover fighter pitting Street Fighter's cast against Tekken's under Capcom rules.
Marvel vs. Capcom 2: New Age of Heroes leans Execution (Grand Arena); Street Fighter X Tekken leans Execution (Grand Arena).
Marvel vs. Capcom 2: New Age of Heroes leans a little harder on execution, though the gap is small.
Marvel vs. Capcom 2: New Age of Heroes
infinite combos and assist timing demand elite hands
Street Fighter X Tekken
Tag combos and juggle timing demand practiced hands
Marvel vs. Capcom 2: New Age of Heroes leans a little harder on reads, though the gap is small.
Marvel vs. Capcom 2: New Age of Heroes
humans bait assists and mix high-low constantly
Street Fighter X Tekken
Human mixups and tag baits require adaptation
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Marvel vs. Capcom 2: New Age of Heroes
fully deterministic engine
Street Fighter X Tekken
Deterministic aside from negligible elements
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Marvel vs. Capcom 2: New Age of Heroes
team order, assist synergy, and matchup knowledge
Street Fighter X Tekken
Gem loadouts and team synergy add a builder layer
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.