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
Demanding platform execution plus a solvable boss-weakness ordering puzzle.

Execution · Practiced Mastery
A classic frenetic shooter that rewards fast reflexes and mastering enemy patterns.
Mega Man leans Execution (Practiced Mastery); The Ultimate Doom 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.
Mega Man
Pixel-precise jumps and shots against brutal fixed stages
The Ultimate Doom
twitch aim and movement drive combat
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man
Robot Masters cycle rigid scripted patterns
The Ultimate Doom
fixed demon patterns, no adaptation
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man
Nothing changes between attempts
The Ultimate Doom
minor spawn and drop randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man
Boss-order weakness routing is a known solvable layer
The Ultimate Doom
weapon routing and glory-kill loops 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.