I've had great experiences dealing with Northern Whitetail Crabs, The Wildlife Group, Nativ Nurseries and St. Lawrence Nurseries. This spring order is my first from St. Lawrence but the customer service has been excellent. I've only heard great things about them. I especially like the fact that they offer trees on standard root stock. It's actually much harder to find trees on Standard vs. Semi dwarf than I originally thought it would be.
I really want to place an order from Big Horse Creek Farm, they're really close to my land. Their ordering system makes it difficult for me personally. They only ship in the fall and orders need to be in by March. They have an excellent selection of trees and rootstock options.