Kabuto and Karin are more or less same thing, they have same chase, Kabuto more defensive with summons, Karin more offensive with poisons. Honestly biggest advantage of a healer is not the healing but the debuff removal, and the best one for that is Jigokudo pain, since he fully clears them from 2 people. If you don't have him next best option would probably be Kabuto and he is easy 5 star, since it's easy to get 1k+ trial credits a day.