I've tasted over 350 bottles. My favorite American distiller at the moment is Buffalo Trace in Kentucky. They're known for the extremely popular Van Winkle, E.H. Taylor and Buffalo Trace brands.
A brand that comes from the Buffalo Trace distillery but is popular by those in the know and less so by casual sippers, is the W.L. Weller brand. It shares the same mash bill as Pappy, but, its aged in different barrels and placed somewhere else in the rick-house. There are several variations for varying price, but I'd be curious to hear what you think about them.