head to head
Neither is simply harder - they are hard in different places. Portal demands more execution; SD Gundam G Generation Cross Rays demands more variance.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.

Optimization · Pure Optimization
Optimizing mecha squad builds and development plans through solvable tactical stages.
Portal leans Optimization (Pure Optimization); SD Gundam G Generation Cross Rays leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Portal
Portal placement timing modest.
SD Gundam G Generation Cross Rays
Turn-based menus - hands are irrelevant
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Portal
No adversary modeling player.
SD Gundam G Generation Cross Rays
Enemy AI follows fixed priorities, never models you
SD Gundam G Generation Cross Rays leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
SD Gundam G Generation Cross Rays
Hit rolls and crits wobble individual turns slightly
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Portal
Pure puzzle-solving optimization.
SD Gundam G Generation Cross Rays
Squad building, unit development and stage routing is the game
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.