head to head
Neither is simply harder - they are hard in different places. Warcraft III: Reign of Chaos demands more optimization; Z1 Battle Royale demands more variance.

Optimization · Grand Arena
Blizzard's hero-centric RTS where build-order theory meets surgical unit micro against humans.

Execution · Grand Arena
An early battle royale shooter where dozens of players loot, drive, and shoot to be the last one standing.
Warcraft III: Reign of Chaos leans Optimization (Grand Arena); Z1 Battle Royale 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.
Warcraft III: Reign of Chaos
Micro of heroes and units decides fights
Z1 Battle Royale
Gunplay, bullet drop, and car control under pressure
Warcraft III: Reign of Chaos leans a little harder on reads, though the gap is small.
Warcraft III: Reign of Chaos
Scouting and out-guessing a human opponent's tech
Z1 Battle Royale
Human opponents rotate, bait, and adapt to you
Z1 Battle Royale leans clearly harder on variance.
Warcraft III: Reign of Chaos
Creep routes and item drops add randomness
Z1 Battle Royale
Loot spawns, drop locations, and gas circles
Warcraft III: Reign of Chaos leans clearly harder on optimization.
Warcraft III: Reign of Chaos
Build orders, creeping routes, and matchup theory run deep
Z1 Battle Royale
Loadout and rotation strategy is a thinner layer
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.