Great thread.
IMHO, I think your initial post is probably the correct one, with maybe WC Fields in second.
So not to derail it, but to maybe move in a tangent & as you alluded to with your spoiler: it really struck me as I’ve been reading the replies how really old all the examples are. Other than maybe Jack Nicholson, I don’t really see any celebrities above who are active any longer or even alive in most cases. I’m wondering why this is?
Is it that there are no distinct voices anymore? (although I wonder if we will see a wave of Trump based characters since he has such a distinctive speaking style)
Is it that the golden age of cartoons has passed?