Can't believe these two haven't been debated yet.
Chris Farley:
Legitimately good. His stuff from SNL is legendary. David Spade has done well for himself, but there was something special about Chris and David's chemistry. Tommy Boy is still one of my favorite movies of all time. Farley was originally selected to play the part of Shrek, and was also in collaboration to make and star in a film about Fatty Arbuckle. Without Farley we now have to endure an endless stream of Kevin James, Hollywood's replacement as the 'heavy funny guy'.
John Belushi:
I really have no right to comment on whether he is overrated or a legit talent. His work and his untimely death were before my time. I have seen bits and pieces of some of his SNL work, and never really sat through any of his movies. He was the biggest influence on Chris Farley, and they both died at the same age of 33.