head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Reads · Competitive PvP
An anime fighting game packing JoJo's whole cast into stylish one-on-one duels.

Reads · Competitive PvP
The 2011 reboot that returned Mortal Kombat to brutal 2D fighting fundamentals.
JoJo's Bizarre Adventure: All-Star Battle R leans Reads (Competitive PvP); Mortal Kombat leans Reads (Competitive PvP).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
JoJo's Bizarre Adventure: All-Star Battle R
Combo execution and punish timing matter
Mortal Kombat
Combo execution and punish timing
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
JoJo's Bizarre Adventure: All-Star Battle R
Human opponents adapt every round, classic fighter mind games
Mortal Kombat
Human opponents adapt; conditioning and counter-guessing rule
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
JoJo's Bizarre Adventure: All-Star Battle R
Full information once matchups are known
Mortal Kombat
Near-deterministic systems
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
JoJo's Bizarre Adventure: All-Star Battle R
Frame data, matchup knowledge, optimal punishes
Mortal Kombat
Frame data and matchup study converge to known answers
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.