John Madden was the man, he said some of the dumbest shit I've ever heard. It's so dumb to the point that it's hilarious. Plus, his ability to point out the obvious is uncanny.

John Madden's Announcing Career. We can only hope the end comes soon for Collinsworth's.
I also like Ken Harrelson, who does White Sox games. Not as much funny, he brings a different approach to announcing games that's fresh. Dan Plesac is a pretty funny guy who does sports for MLB Network as well.