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 · Competitive PvP
Class-based team shooter with deep mind games.

Execution · Grand Arena
Elite-focused 40K RTS where power node pressure and ability-chain timing test both micro and opponent reading.
Team Fortress 2 leans Execution (Competitive PvP); Warhammer 40,000: Dawn of War III 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.
Team Fortress 2
Projectile aim and rocket jumps reward hands
Warhammer 40,000: Dawn of War III
Elite ability chains and walker micro have strict timing demands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Team Fortress 2
Spy/sniper duels are pure prediction
Warhammer 40,000: Dawn of War III
Three-race elite compositions must be scouted and countered
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Team Fortress 2
Random crits and spread inject RNG
Warhammer 40,000: Dawn of War III
Power node variance and ability cooldown RNG add moderate uncertainty
Warhammer 40,000: Dawn of War III leans a little harder on optimization, though the gap is small.
Team Fortress 2
Class loadouts and map routes solvable
Warhammer 40,000: Dawn of War III
Elite point allocation and doctrine selection are defined optimization problems
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.