Which headphones are better the bose QC 15 or the sennheiser noise canceling model?

They are both great headphones but I think it comes down to price. Bose QuietComfort 15 Acoustic Noise Cancelling Headphones cost $299.95 and are great but you can also get Sennheiser HD 558 Audiophile Headphones with an Internal Surround Reflector on sale for $169.95. Look in the two links below to find out more information on them. Hope this helps!