You are going to have to have some idea of what you want. Then give a narrow choice to the masses eager to help you. If you think your head is about to explode now...just ask a question like you did and get 1000 new different opinions!

So start with what you want....a long handled brush, in horn, Badger (but what quality?),decent back bone. How do you lather? How much are you willing to spend for the brush? What knot size? Are you willing to do some of the work? Is a horn handle essential? If there is a mismatch between want and budget, what are you willing to compromise on?