Tomoyuki Yamashita deserves a spot more than Yamamoto. Malaya and Singapore were Japan's most impressive victories.
Yamashita rates pretty high in most people's books. I don't know enough of his story yet - but I think I need more than Malaya and Singapore to rate him higher - was he also in the Philippines in 1944 ? Anyway - Yamammoto played a part in the early victories as well as the Guadalcanal Naval battles - he's more of an icon of the war if you ask me. But granted any extended list should include Yamashita.