Which Headset should I Buy?

First on your list should be comfort. You need to find a pair that you will be comfortable wearing.

Second is audio quality, unless your thing is audio quality, then reverse these two. If it doesn't sound good then it isn't going to be any fun gaming with them on.

The third most important thing is what I call, Cheetos stain resistance... ok that was a joke.

But really it all comes down to what you like. So, go to a store and try some out if you can. If not read reviews and try to get an idea from those. In many cases reviews will be of little help. These aren't GPUs or CPUs that will provide predictable levels of performance, they are I/O devices, and people just like what they like.