Although his first interaction with Wallace was lying and manipulating him .
I think, rather then ranking them, each mentor Wallace has had have taught him something in his road to becoming a hero.
Meena taught him how to control his powers when he first started out.
Slade taught him new ways to apply his powers and about the "real" world.
Wally taught him to believe in himself and what it means to be Kid Flash.
Barry taught him what it means to be a hero.