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
Out-executing and out-predicting another human in frame-precise duels.

Execution · Competitive PvP
The classic 'dream match' team fighter widely held as KOF's most balanced competitive entry.
Super Street Fighter IV: 3D Edition leans Execution (Competitive PvP); The King of Fighters '98 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.
Super Street Fighter IV: 3D Edition
Links, anti-airs and motion inputs gate every level of play
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.
Super Street Fighter IV: 3D Edition
Footsies and conditioning a human opponent decide matches
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.
Super Street Fighter IV: 3D Edition
Almost fully deterministic once inputs land
The King of Fighters '98
Near-fully visible game state
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Super Street Fighter IV: 3D Edition
Frame data, matchup knowledge and punish routes underpin everything
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.