I guess it all depends on the requirements of the user, the money they want to spend, how much abuse it's going to get, do you actually want it to clean or just give the appearance of clean, the cost of bags and belts. The Sanitaire SC9180, SC5505, SC5500, SC5815, SC5713 all have OBT and clean very well. All but the last two use poly v or cogged belts that won't need to be replaced that often.