It's unfair to compare any comedian to John Candy. And Candy's SCTV partner Martin Short is very funny--not just on that Canadian TV series but as Jiminy Glick. How can you not laugh at Glick?
As for Steve Martin--he reminds me of Andy Kaufman, whom I find funny in a very dry (but not British dry), deadpan, throwaway way. Fred Willard is funny (okay funnier) in the same manner.
Speaking of SCTV, Eugene Levy is devastatingly funny, just not as a traditional comedian. He creates characters that you simultaneously laugh at and find yourself in.
But John Candy was the greatest of them all. Damn, I miss him.