One thing about crimped alfalfa--if there are blister beetles in the field, the crimping will kill them and leave them in the hay. If the hay is cut without crimping, the beetles will generally leave the hay before it is baled. If the hay comes from an area with blister beetles, check it carefully prior to feeding. Otherwise--crimped hay is often nicer--more leaves, and a little softer hay because it dried quicker and is less brittle. I don't remember a horse ever refusing to eat crimped hay.