I like the UCL lens. I have a few medium orange peel aluminum reflectors so I don't need the diffuser coatings. The borofloat lenses are probably stronger & more temperature resistant if that is a consideration. I'm about ready to order a couple more, so I'm interested in seeing if anyone comes up with any other good points.
UCL will be the most clear / brightest. I am starting to like Abrasion Resistant Polycarbonate though - really tough and does not scratch as much as people worrry about.