head to head
Neither is simply harder - they are hard in different places. Tekken Tag Tournament 2 demands more execution; Warcraft III: Reign of Chaos demands more variance.

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

Optimization · Grand Arena
Blizzard's hero-centric RTS where build-order theory meets surgical unit micro against humans.
Tekken Tag Tournament 2 leans Execution (Grand Arena); Warcraft III: Reign of Chaos leans Optimization (Grand Arena).
Tekken Tag Tournament 2 leans clearly harder on execution.
Tekken Tag Tournament 2
Tag combos and partner launcher extensions demand high motor precision
Warcraft III: Reign of Chaos
Micro of heroes and units decides fights
Tekken Tag Tournament 2 leans a little harder on reads, though the gap is small.
Tekken Tag Tournament 2
Tag crash timing and incoming character reads against humans are constant
Warcraft III: Reign of Chaos
Scouting and out-guessing a human opponent's tech
Warcraft III: Reign of Chaos leans clearly harder on variance.
Tekken Tag Tournament 2
No RNG; all information is visible
Warcraft III: Reign of Chaos
Creep routes and item drops add randomness
Warcraft III: Reign of Chaos 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
Warcraft III: Reign of Chaos
Build orders, creeping routes, and matchup theory 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.