Kisame wins this
--he is a bad match up for danzo, as he proceeds to suck him dry through his samehada whenever he attempts to attack him, and his chakra absorption abilities and bijuu level reserves enable him to outlast danzo quite easily
--danzo has no real way of hurting kisame when he has samehada repairing all of his damages for him, and with water prison jutsu immobilising him, at CQC means that kisame can rip him to shreds with samehada or suck him dry,
--genjutsu is also not happening when kisame can use his water clones to reduce its probability and has samehada which is capable of breaking him free,
--once kisame merges with samehada, danzo has no way of hurtin him at all, and he uses the water dome to suck danzo dry and feed him more chakra constantly, thus outlasting danzo with ease,