If you're talking about the MS jutsu:
1. Shisui (KA unless we know it's able to be countered)
2. Obito/Kakashi (Either Kamui is haxxed)
3. Itachi (Totsuka Blade, Yata Mirror, Susano, Amaterasu, Tsukuyomi)
4. Sasuke (Susano, Amaterasu, Kagutsuchi)
5. Madara (Susano and Tsukuyomi - which is debatable, we don't know his 3rd power but I'm guessing it's useless)
If you're talking about how they rank when they had their MS:
1. Obito (Defensive Kamui, Katons on Madara's level, Hashirama cells, Mokuton, Izanagi)
2. Itachi (Tsukuyomi, Amaterasu, Susano with Totsuka Blade and Yata Mirror, Izanami, great weapon usage, clone feints, 2 elements) OR Kakashi (very versatile and his Kamui is very effective and fast but has low stamina)
3. Sasuke (Spammed too much and almost went blind within a month of having it - he does have Amaterasu, Kagutsuchi and Susano + Raiton such as Kirin and the Chidori varients + C and B rank Katons)
4. Madara (MS Madara = MS Izuna < Tobirama < Hashirama, S rank Katons, Gunbai but less versatility than Sasuke)
5. Shisui (Yes he had KA but it wasn't much use to him)