I'm not sure if we are talking about game show hosts, commercial announcers, radio announcers...
But, I would be remiss in not mentioning one of my favorites, the late Larry Lujack of Chicago fame. He was fantastic at being an uptempo top 40 jock, but in a second he could bring it down and just converse in a natural style, still with that great voice. I think he probably thought is was kind of a joke that he had to be this "rock jock" over intros, then bring it down when just talking to his audience. Few could do it quite like him. And his commercial copy reads were priceless, as he would giggle if the copy made little sense and he would call it out. I heard some advertisers requested him just for that reason!