head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Practiced Mastery
A modern Gears entry spanning campaign, Horde, Escape, and ranked versus.

Execution · Practiced Mastery
Prequel chronicling Noble Team's doomed defence, with armour abilities reshaping multiplayer.
Gears 5 leans Execution (Practiced Mastery); Halo: Reach leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Gears 5
Movement tech and shotgun duels remain the core test
Halo: Reach
DMR precision and armour-ability timing
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Gears 5
Ranked versus rewards out-thinking human opponents
Halo: Reach
Multiplayer rewards predicting human movement
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Gears 5
Escape and Horde inject some run variance
Halo: Reach
Loadouts and spawns add small swings
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Gears 5
Character ultimates and map control are learnable
Halo: Reach
Ability matchups and map knowledge
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.