Kabuto had more than just snake sage mode going for him. He had the abilities of other shinobi in him. For example snake sage mode is not what allows him to avoid all harm but Oro and suigetsu powers as well as karin with her uzumaki recovery speed. His sense of perception was much better than naruto and jiraiya's jutsu but if you ask me jiriaya or naruto(even without km) vs kabuto in sage mode( no edo tensei) would win.