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

Execution · Twitch Chaos
Kart racing execution moderated by item randomness and learnable track routes.

Execution · Twitch Chaos
Sloppy kart handling where random items swing races more than driving skill.
Sonic & All-Stars Racing Transformed leans Execution (Twitch Chaos); South Park Rally leans Execution (Twitch Chaos).
Sonic & All-Stars Racing Transformed leans a little harder on execution, though the gap is small.
Sonic & All-Stars Racing Transformed
Drift timing and transforming vehicle control reward practice
South Park Rally
Loose kart handling still rewards clean driving
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Sonic & All-Stars Racing Transformed
Human racers add light positional mind games
South Park Rally
Human racers in versus add slight prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Sonic & All-Stars Racing Transformed
Item rolls regularly upend race positions
South Park Rally
Random weapon pickups swing race outcomes
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Sonic & All-Stars Racing Transformed
Track shortcuts and drift-boost routes are learnable
South Park Rally
Track shortcuts and item timing are learnable
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.