I'm looking at the Bose QC15s versus the new Denon D600s.
I'm more of a mainstream listener and a basshead so I do put some value and importance on powerful bass. I listen to a wide variety of music, but also a lot of top iTunes songs. I know comparing these two headphones isn't really comparing apples to apples and some may say the Bose's sound quality is laughable, but I would still like your recommendations and opinions on these two please :)
What makes you interested in the Bose QC15? If you want isolation from ambient noises, then these are the best; soundwise these are a poor choice for anything above $150. Also, the Denon D600 is supposedly not all that bass heavy based upon the review here on Head-fi, so it may not suit you. The older Denon line (D2000/D5000) may be better aligned with your tastes.
If you are a basshead, it is important to know if you like the thumping bass, or the deep bass that shakes your head, that is not as audible. Check out this thread for some recommendations to satisfy your basshead cravings at your appropriate budget.