Itachi, no question about it.
Itachi-totally mastered mangekyou sharingan.
Sasuke-one of the most unmastered mangekyou sharingan, he became blind in about 2-3 days.
Kakashi-Ok, it is good, but the drawback and aim is worse, making it vulnerable to others.
Madara-He has EMS, we are talking about MS, so he awakened MS first, so we cannot say that he mastered his MS totally. You cannot learn swordfight alone, without any master.
Izuna-well, it may be strong, we don't know much about it.
Shisui-Only ONE power with both MS eyes with a decade gap? are you kidding? if it is repelled somehow, it is useless.
