head to head
Neither is simply harder - they are hard in different places. Gyakuten Kenji 2 demands more variance; Portal demands more execution.

Optimization · Pure Optimization
A mystery visual novel testing deductive matching of evidence to scripted contradictions.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Gyakuten Kenji 2 leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Gyakuten Kenji 2
Reading text and presenting evidence has no motor test
Portal
Portal placement timing modest.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Gyakuten Kenji 2
Witnesses are scripted contradictions, not adapting minds
Portal
No adversary modeling player.
Gyakuten Kenji 2 leans clearly harder on variance.
Gyakuten Kenji 2
Case truths are hidden information revealed on rails
Portal
Deterministic chambers; no randomness.
Portal leans a little harder on optimization, though the gap is small.
Gyakuten Kenji 2
Matching evidence to testimony is a fixed logic puzzle
Portal
Pure puzzle-solving optimization.
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.