If you haven't done so, please listen to them both at the same store with speakers similar to the ones you plan to use and pick the one you like better!!!
That said, I voted for the RX-V650, soley on the fact that's what I bought. I had a similar decision last year. I was going between the RX-V650 and the AVR-1805 (the 1905's predessor). I knew I couldn't go wrong with either one, which made it such a tough choice, but went with the Yamaha because I liked the way it sounds with music just a hair better than the Denon, but I prefer a more upfront sound. You may not. The RX-V650 is great with movies and the YPAO does a pretty decent job it you aren't into doing all the speaker calibrations yourself. (Not sure if the Denon has that). Which ever you decide on, enjoy!