Only you can answer that!!
Personally, when I purchased my CS-515 I found it to be much more convincing than the Denon, although I'd strongly recommend picking up the Onkyo unit without speakers for about £230 and spending money on some decent speakers. The Onkyo speakers are OK but combining the unit with something from the likes of Q Acoustics, Tannoy or Monitor Audio (I picked up my Bronze 2s for £130 brand new) will give you significantly better sound. Many hi-fi dealers stock both the Denon and Onkyo units so book a demonstration and ask to try different budget speakers with each to see which you prefer.