head to head
Neither is simply harder - they are hard in different places. All Guns on Deck demands more variance; Portal demands more optimization.

Optimization · Pure Optimization
A naval strategy-action hybrid testing fleet management and conquest planning.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
All Guns on Deck leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans a little harder on execution, though the gap is small.
All Guns on Deck
Light action combat with modest timing demands
Portal
Portal placement timing modest.
All Guns on Deck leans clearly harder on reads.
All Guns on Deck
Faction AI is scripted, no adaptive prediction
Portal
No adversary modeling player.
All Guns on Deck leans clearly harder on variance.
All Guns on Deck
Battle outcomes have some rolled randomness
Portal
Deterministic chambers; no randomness.
Portal leans clearly harder on optimization.
All Guns on Deck
Fleet management and strategic conquest is the core layer
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.