Buffalo dvd drives used to be the virtually the same as Pioneer, just with proprietary firmware that made them slightly different. I'm not sure this still holds true.
Is there a specific model number you are considering? We generally advise getting a full sized external drive with its own power supply rather than a slim drive that uses power from the usb connector. The slim drives don't seem very robust, and there are potential problems from using the power feed from the usb line.