Pain, Itachi, Kisame
Konan is beast but against Kisame and Itachi, there is no comparison. She may have been beast but Tsukoyomi would leave her too fatigued and Kisame was on the same level as the tailed beasts, so no contest.
Konan was Pain's subordinate for a reason, not only did they grow up together but she herself called nagato *unbeatable* which means she admitted to being on a lower level than him.
Orochimaru is a beast as well but he tried to take Itachi's eyes and failed, Kisame was paired with Itachi and his sword could leave orochimaru with not enough chakra to use his snake revival jutsu's, slowly but surely Kisame would have won. As for Pain...please Orochimaru couldn't handle 4 tailed naruto, how is he supposed to handle pain?
Sasori would be a good fight, but compared to Itachi, Kisame, and Pain, even his thousand puppet jutsu cant keep up with tsukoyomi, Kisame's sword fusion form, or the raw power of Pain.
Kakuzu and Hidan were both outclassed by Naruto in his normal state, so if they couldnt fend off them then my three picks would be too much
Zetsu is a support Ninja so by himself he would be devastated.
Deidara would succumb to the raw power of susano'o, Pain's edo tensei and earth devastation jutsu's, and Kisame could simply suck the chakra dry from any of his C# explosives.
EDIT: Tobi, Itachi, Pain.
same theories but replace Kisame with Tobi, he has already proven himself to be the best, and Kisame swore allegience to him so he would beat the other members of akatsuki hands down.