As far as master's go, while it is a subjective term, I can only think of a few. Like Jason said, Steven Assael's work is amazing in person, and he's not that old yet so he has plenty of time to outdo his already great work. And his teacher David Leffel, his work in person is some of the most amazing stuff I ever seen. I see Leffel and Rembrandt as equals, he stuff is that good.
And Schmid I think is right up there. But Alex Ross? wtf, are you kidding?
@Parker D- Sergios drawings are good, but his paintings are pretty damn all over the place.
edit: this is like the first time I've posted in fuckin' ages. Freakin' wierd.
Being stubborn towards humanity since 1982