My readers tell me that Dallas McKennon was the first voice of Tony. He also did Snap, Crackle, and Pop and other cartoon characters such as Gumby and Archie.
The most famous voice for Tony is provided by Thurl Ravenscroft. Surely, "They're Grreat!" is one of the most famous phrases in marketing history. (Right up there with, "I can't believe I ate the whole thing!")