Old Maul 10/10. Old Maul knows his younger self in every possible smallest aspect. TPM Maul surely didn't yet know how powerful he will be 30 years later, how physically fit he is going to be, what changes in his lightsaber style he will develop.
Even if Maul atrophied somewhere, or developed more Force mastery somewhere, it's irrelevant in comparison to his absolute knowledge of what he once was.
It's simple as that.