Who is/was the better singer, Nat King Cole or Johnny Mathis?

Both were great. In different ways. As a total musician, probably Nat King Cole.

Nat has the better voice.

Taking nothing away from Johnny Mathis (who is a terrific singer), I think Nat King Cole (RIP) was even better.

Both great, but Nat wins by half a hair.

easily Nat King Cole

Nat King Cole

NKC