This is an example, from a hybrid forum post, of what I'm calling a "road rotor". I think this design looks a little more functional than most MTB rotors. MTB rotors seem to be getting more wild-looking by the week, with all sorts of odd hole drill patterns, spoke patterns, disc shapes, etc, where form may be the predominant design priority. I generally like "road rotors" because they seem to look the business more. Just simple, round, rotors. I figured the differences in design is due to the nature of the application, road bikes having more of a sustained duty cycle than expected on a MTB, where braking is probably more intermittent in nature.