I have one Bobbi Brown Brush and I really like it. For cheaper alternative I like Sonia Kashuk brushes from Target. I also have some Chantecaille brushes and they are nice. My favorite Kabuki brush is from Aromaleigh.com. I use it to apply loose powder and it works great.
Most of my brushes are Sonia Kashuk, but I have one from Sephora and MAC that I really like. I'd eventually like to replace all my SK brushes w/higher end ones. I think I want to start with the Bobbi Brown Face Brush and MAC #219.