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 · Grand Arena
Hero shooter with team-up ability synergies.

Execution · Competitive PvP
Class-based team shooter with deep mind games.
Marvel Rivals leans Execution (Grand Arena); Team Fortress 2 leans Execution (Competitive PvP).
Marvel Rivals leans a little harder on execution, though the gap is small.
Marvel Rivals
Hero aim and ability timing
Team Fortress 2
Projectile aim and rocket jumps reward hands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Marvel Rivals
Team-fight cooldown trading is prediction
Team Fortress 2
Spy/sniper duels are pure prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Marvel Rivals
Map and team comp roll affects
Team Fortress 2
Random crits and spread inject RNG
Marvel Rivals leans a little harder on optimization, though the gap is small.
Marvel Rivals
Hero synergies and team-up combos deep
Team Fortress 2
Class loadouts and map routes solvable
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.