This's a wide open question. There are many factors that would influence what type of body one wanted. Are you fighting self-defense?Sport Karate?....The list goes on and on.
Let's try self-defense. Do you want go with the old stereotypes..Big and strong/Goju, or Quick and fast Shorin?
(I don't believe in the old big-Goju,fast-Shorin line.)
I don't think there's a ideal Karate body. I think that the topic has too many variables. It does give one food for thought though.
Having thought about it I have decided that my ideal Karate body will always be about 15 lbs less than whatever my current weight is at that time.Oh well.

keep training, Mark