An L-shaped plug is better if the jack is on the left or right side of the device, so that the cable isn't bent, and is less likely to break when the device is in your pocket.
31% have it
14. has a straight plug
A straight plug is better when the jack is on the top or bottom of your player.
55% have it
15. has an over-the-ear form
Comfortable full-size form with earcups that fully enclose your ears. This model is loved for its increased sound isolation and the fact that it won't leak sound to your neighbors. It offers potential for maximum bass and loudness levels.
42% have it
16. number of microphones
More microphones result in better sound quality and enable the device to filter out background noise.