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

Optimization · Pure Optimization
A gentle turn-based system easily solved by build and gear choices.

Optimization · Pure Optimization
CD Projekt's first RPG, a dark fantasy of monster contracts and morally gray choices.
South Park: The Stick of Truth leans Optimization (Pure Optimization); The Witcher leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
South Park: The Stick of Truth
Timed attack and block prompts add light input demands
The Witcher
Rhythm-click combat needs only loose timing
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
South Park: The Stick of Truth
Enemies follow fixed turn-based scripts
The Witcher
Enemies follow fixed styles and weaknesses
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
South Park: The Stick of Truth
Minor damage rolls; encounters are otherwise fixed
The Witcher
Some unknown quest outcomes on first play
The Witcher leans a little harder on optimization, though the gap is small.
South Park: The Stick of Truth
Build, gear and ability choices comfortably solve every fight
The Witcher
Signs, potions, and style matchups form the real 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.