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
The classic 'dream match' team fighter widely held as KOF's most balanced competitive entry.
Marvel vs. Capcom 2: New Age of Heroes leans Execution (Grand Arena); The King of Fighters '98 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
The King of Fighters '98
Strict inputs, short hops, tight punishes
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
The King of Fighters '98
Human opponents constantly adapt and condition you
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
The King of Fighters '98
Near-fully visible game state
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
The King of Fighters '98
Team order and matchup theory reward study
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.