Low Impedance high sensitivity are usually used for portable use, since they don't require much power, and are easy to drive. Low impedance headphones usually want more current, while high Impedance wants more voltage swing.
Neither one is "better sounding" as they both can sound great. If you had high Z (impedance) portable headphones, you would be up s**t's creek without a paddle lol. It's more of a preference of application and amplifier matching for choosing impedance. For example, planar magnetic drivers are low Z, low sensitivity, so they require a lot of current, but they also have a constant impedance vs frequency generally speaking, whereas dynamic headphones have varying impedance vs frequency. It's all pros and cons, neither is superior