While I was being trained to fly I used the rental David Clark H10-13.4 and the ASA AirClassics HS-1A headset, and between the two, the David Clark is just a lot more comfortable when I was on navigation training.
After I earned my license though, I bought the Sennheiser S1 Passive headset while Sennheiser had a discount on the headset. The Sennheiser was a bit more comfortable then the David Clark H10-13.4, but then I'm paying a good $30 more then the David Clark.
It's all really your choice. You just have to pop in to your aviation club and try the headsets out (if they sell them), or just find a nearby aviation store. I got lucky with the Sennheiser because I didn't try it before and there's a decent chance it doesn't fit well to my head.