As a student I have been hiring from my club David Clark's with Gel earseals.
As a glasses wearer the gel seals make a big difference, but so does how carefully I put them on and position the headset on my head (any gaps mean a big increase in sound). After a couple of hours flying with the DCs I was starting to get a sore head from the clamping pressure.
My plan (once I get my PPL) is to treat myself to something that will probably break my budget...
The advice I've got from others is to spend as much as you can afford as you wont regret it later. There are fitting differences between different headsets which mean that the A20 wont suit some people (and the same for the Zulu ) so try a number of different ones on in a shop. I'm told some shops also let you "try before you buy". Worth doing if making an investment (which is what buying a top end headset is).
Happy flying!