Each breed has different breeders that are "tops", but a good place to get a "start" from is Superior Farms in Yukon, OK.
They bought out all the "big name" breeders and are now selling show-quality stock. It's a good place to get the starter flock from, so you can see the differences between production and show birds. They have the top Brahmas, and their Silver Laced wyandottes are to DIE for. Their gold-laced are darn good too.
As for Wyandotte breeders, that's gonna be difficult. I suggest contacting Katy on this board to see if she knows of anyone. I'm into Langshans and Barred Rocks, so I know little to nobody in the Wyandotte area.