Buy longer than you think you need. Dorm outlets are never near the desk, and the cable in the box assumes you live somewhere sensible. Braided ones survive a year of being wound around a laptop.
The library is never as quiet as you need it to be at two in the morning in reading period. This is a concentration purchase, not an audiophile one. I wore mine until the earpads flattened, then bought pads instead of a new pair.
How waterproof it is tells you more about how this ends up than the wattage does. It will go to a beach, a bathroom, and a tailgate, and at least one of those involves it getting knocked over.
For the days that start at nine in the morning and end at nine at night. Check for pass-through charging before you buy, because most inexpensive ones will not charge themselves and your phone at the same time.
