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 · Competitive PvP
Out-executing and out-predicting another human in frame-precise duels.
Marvel vs. Capcom 2: New Age of Heroes leans Execution (Grand Arena); Super Street Fighter IV: 3D Edition leans Execution (Competitive PvP).
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
Super Street Fighter IV: 3D Edition
Links, anti-airs and motion inputs gate every level of play
Same score on reads - 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
humans bait assists and mix high-low constantly
Super Street Fighter IV: 3D Edition
Footsies and conditioning a human opponent decide matches
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
Super Street Fighter IV: 3D Edition
Almost fully deterministic once inputs land
Marvel vs. Capcom 2: New Age of Heroes leans a little harder on optimization, though the gap is small.
Marvel vs. Capcom 2: New Age of Heroes
team order, assist synergy, and matchup knowledge
Super Street Fighter IV: 3D Edition
Frame data, matchup knowledge and punish routes underpin everything
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.
full breakdown
Marvel vs. Capcom 2: New Age of Heroes →
full breakdown
Super Street Fighter IV: 3D Edition →