My list is mostly based on the people who specializes in a certain form if they is someone worth mentioning for it otherwise.
Shii-Cho- I'm not sure but I will give it to Kit cause of his smile
Makashi-Dooku obviously
Soresu-Obiwan
Ataru-Yoda
Djem So- This is tough you have Vader/Skywaler, Bane and Luke Skywalker, I'm going to give it to Luke.
Niman-Not sure it is the "balanced" style and I don't know of single master of it but there are a lot of saber masters to know it. Such as Kavar, Kasim and Cin Drallig. I think I would lean towards that latter but I am not really sure on this one.
Vapaad-Mace obviously
Juyo-Maul since (Sidious is master of all forms save vapaad but he seems to use a lot parts of it so I'm not sure if his form could be classified as one strict form but if it was it could be this one and I would give it to him then)
Jar Kai- I'm going to give this to Grievous