head to head
Neither is simply harder - they are hard in different places. Dragon Quest XI S: Echoes of an Elusive Age demands more variance; Portal demands more execution.

Optimization · Pure Optimization
A traditional turn-based JRPG where optimising skill trees and Pep power timing defines progression through scripted monster encounters.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Dragon Quest XI S: Echoes of an Elusive Age leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Dragon Quest XI S: Echoes of an Elusive Age
Classic turn-based; no twitch input at any point
Portal
Portal placement timing modest.
Dragon Quest XI S: Echoes of an Elusive Age leans a little harder on reads, though the gap is small.
Dragon Quest XI S: Echoes of an Elusive Age
All monsters follow fully scripted AI routines
Portal
No adversary modeling player.
Dragon Quest XI S: Echoes of an Elusive Age leans clearly harder on variance.
Dragon Quest XI S: Echoes of an Elusive Age
Metal Slime encounter rates and rare drops carry meaningful RNG
Portal
Deterministic chambers; no randomness.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Dragon Quest XI S: Echoes of an Elusive Age
Skill tree routing, Pep power sequencing, and party healing economy reward planning
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.