I just threw the best part of $1400 at a Bose X headset. Given the cost, It wasn't a decision made lightly. The headset is very good, and 20 or so hours later I don't regret the purchase. It does well to eliminate much of the cockpit noise in the Moonies I fly. Before that I used a David Clark H20-10 that I purchased secondhand on ebay for $160. The DC is still going strong, but I found on longer flights (3hrs plus) that I was really quite fatigued and that my ears would ring. But the main reason for getting the Bose headset was that I tried a loan unit and it made ATC so much easier to hear clearly. In a stressful learning environment it really helps to know that you're not going to be constantly asking a progressively more annoyed controller to "say again".
My decision to go for the Bose is based on the fact that I've chosen to fly for a living. If I was going to stop at my PPL and fly occasionally, I would have stuck with my DC - which is extremely well built and hasn't missed a beat over many years of use. I have tried the cheap altronics unit and imho it is suitable only for use on a ride-on mower. The DC H10-30 that most people seem to use as students is also very good, but many complain of discomfort after a few hours due to the "clamping force" on the sides of your head, or headaches due to continuous pressure on the top of your head. You can buy gel-earpads as an upgrade for the DC H10s which will help a bit. The H20-10's come with gel-pads and an adjustable soft elastic band " aka Comfort Cover Head Pad" that acts as a cushion on the top of your noggin..
It's such an individual thing that I would say, if you can, try to borrow a few different headsets, and find the one that feels best for you. Maybe the local pilot shop has loan units from different manufacturers (they seem to where I fly)
If you are willing to spend real $$ on an ENC headset, it seems there are 3 major players (DC, Bose and Lightspeed). I have read many reviews that say that the DC one (the H10-13X) is noticably inferior to the "Bose Aviation X" and the "Lightspeed Zulu". The Bose is just a headset with ANC and no passive attenuation, whilst the Lightspeed Zulu has ENC and a small amount of passive attenuation plus a bluetooth connection and a hardwired input for an mp3 player or mobile phone.. Both Bose and Lightspeed have a 5yr warranty. The Lightspeed Zulu seems to cost about $950 around the traps, and the Bose X about $1500.. I didn't have the option to try the Zulu so I ended up with the Bose.
I found it difficult when shopping for the Bose headset to find reviews that had hard comparisons in terms of attenuation, as most of the comparisons I found were sponsored by the companies that make the headsets.
I know of quite a few guys that have had success buying perfectly working headsets on ebay (me included), but I guess there's always a risk of getting a dud.
Hopefully that helps a little bit, I'm sure others here will have some useful suggestions.
Steve.