I use a Jasmine Easy Spinner with a 18" hoop and I really love it. You can rotate the hoop 360° and because of a swivel ball you can adjust the position of the hoop very easily. You can also adjust the height and the floor stand is very stable with it's base plate, even when working on big quilts.
I must admit the Jasmine is quite pricey but for it was really worth to spend the money.
I recently read here on the board that Jasmine closed it's online shop and I don't know if these hoops are still available.