After touring Kamaka, KoAloha and Kanile'a, Kamaka makes the most ukes. They are much more automated than the other two. Fred Kamaka proudly pointed out their specially designed machines that make the necks and bend the sides and how behind they got in filling orders when one of them broke down.
I'd then say KoAloha is second with Kanil'ea in third place, based on factory size, the number of ukes in racks in various stages of completion and the number of employees I saw.