I would get closed-back headphones. Impedance rating will depend on what you'll be connecting them to. Over-the-ear is probably better than on-the-ear, but it depends on your personal preference. Sony 7506 are the industry workhorse headphones - over-the-ear, closed-back, relatively high-impedance, durable. Sony 7502 is the little brother, but they're on-the-ear, lower impedance, still durable. A super cheap option would be the Tascam TH-02 with lower impedance. A more expensive option would be Audio-Technica ATH-M50x with lower impedance. Here's a good explanation for impedance: http://turntablelab.com/pages/headphone-buying-guide-what-is-headphone-impedance Hope that helps.
