head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Execution · Grand Arena
Fast arena shooter with deep loadout tuning.

Execution · Grand Arena
A tactical hero shooter decided by aim duels and adapting to human opponents.
Call of Duty: Modern Warfare III leans Execution (Grand Arena); Valorant leans Execution (Grand Arena).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Modern Warfare III
Fast TTK punishes any aim error
Valorant
One-tap aim and crosshair placement decide most duels.
Valorant leans a little harder on reads, though the gap is small.
Call of Duty: Modern Warfare III
Sliding and pre-aim duels reward prediction
Valorant
Humans constantly adapt peeks, fakes, and ability timings.
Call of Duty: Modern Warfare III leans a little harder on variance, though the gap is small.
Call of Duty: Modern Warfare III
Spawn flips and map traffic add noise
Valorant
Light spray RNG and unknown enemy positions.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Modern Warfare III
Loadouts, perks, attachments heavily tuned
Valorant
Agent comps, util usage, and economy are studyable theory.
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.