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.

Reads · Grand Arena
Three-faction Cold-War RTS with naval combat where faction asymmetry and multi-front pressure are the core tests.

Execution · Grand Arena
Hero-driven squad RTS where wargear optimization and ability timing combine with reading aggressive opponents.
Command & Conquer: Red Alert 3 leans Reads (Grand Arena); Warhammer 40,000: Dawn of War II leans Execution (Grand Arena).
Warhammer 40,000: Dawn of War II leans a little harder on execution, though the gap is small.
Command & Conquer: Red Alert 3
Naval and air micro alongside base-building taxes player bandwidth
Warhammer 40,000: Dawn of War II
Hero ability activation and squad retreat timing are mechanically demanding
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Command & Conquer: Red Alert 3
Three-faction asymmetry means opponent choices must be constantly predicted
Warhammer 40,000: Dawn of War II
Opponent army composition and hero focus must be predicted
Warhammer 40,000: Dawn of War II leans a little harder on variance, though the gap is small.
Command & Conquer: Red Alert 3
Ore spawning and naval choke variance add moderate uncertainty
Warhammer 40,000: Dawn of War II
Retreat damage, wargear drops, and map control variance add uncertainty
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Command & Conquer: Red Alert 3
Production order and defensive placement are learnable but more flexible
Warhammer 40,000: Dawn of War II
Wargear builds and ability upgrade sequences are optimizable
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.