When shopping for a headset, keep in mind that this is one item that will be used quite extensively.
Look for a headset that has a great fit. While behind the ear headsets look flatering to the hairline, they are not much for comfort. Look at the ear cushions and how the mic placement was designed.
Look at the cord diameter of the headset and the quality if the jacks. If it looks like any of these items will fail easy from your desk chair wheels or by having the headset pulled from your head when you forget to take it off, do not buy it. Instead of buying a bunch of cheap headsets, try getting one "GOOD" headset.
Some of the USB headsets have their own sound card built into the line. This is great if you do not want to put a sound card in your computer, however not so good if you have a cutting edge sound card with special programming that enable you to hear special sounds. With a USB headset that has a sound card built in the cord/headset, you must use the attached sound card to use the headset.