Whatever you can wear for hours on end that won't give you a headache. I wore my DC's, 13.4's, I think, all through flight instructing and thought they were comfy enough. Then I started flying the bro, and I was getting the worst headaches from the noise and the weight of the headset after 14 hour 8 leg days. Even wearing earplugs underneath wasn't enough. Getting the Bose aviation headset (monthly payment plan, baby!) was the best decision I could have made. They're expensive, but how much do you value your hearing? On the RJ, I rarely use the noise cancelling now unless I'm on the 700 with the noisy fans, but the comfort factor is worth it.