Either one will do just fine. But no one can answer the question but you. The only way to find out for yourself is to buy one of each and try them in your home...... not someone elses home or retail studio..... your home...... where you are comfortable and familiar in your surroundings.
I've auditioned a Denon DRA-395,which I found to be rather lifeless, anemic on the low end and a generally painful edge to the sound. I doubt the 685 is dramatically different.But, that's me, my ears and my home,your results will be different.
The C720BEE I've not heard, but it's amp section is the same as the C320BEE amp which is generally regarded as a well rounded unit. Again, opinions can be cheap,try it for yourself.
If you're in the USA, try buying the Denon from Crutchfield. They have a excellent return policy if you need it. Free shipping to and from to boot.
Good luck , Garth