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.

Execution · Grand Arena
A tag-enhanced Tekken that multiplies execution demands and opponent reads by adding partner management to every exchange.

Execution · Grand Arena
A hyper-fast tag fighting game defined by three-character teams and touch-of-death combos.
Tekken Tag Tournament 2 leans Execution (Grand Arena); Ultimate Marvel vs. Capcom 3 leans Execution (Grand Arena).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Tekken Tag Tournament 2
Tag combos and partner launcher extensions demand high motor precision
Ultimate Marvel vs. Capcom 3
Long touch-of-death combos demand elite hands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Tekken Tag Tournament 2
Tag crash timing and incoming character reads against humans are constant
Ultimate Marvel vs. Capcom 3
Mixups and assist baits versus adapting humans
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Tekken Tag Tournament 2
No RNG; all information is visible
Ultimate Marvel vs. Capcom 3
Almost fully deterministic
Tekken Tag Tournament 2 leans a little harder on optimization, though the gap is small.
Tekken Tag Tournament 2
Tag team pairings and shared health management reward deep preparation
Ultimate Marvel vs. Capcom 3
Team composition and matchup knowledge run deep
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.