Im in the process of buying a stereo amp and I am now confused between Denon and Yamaha.
Denon claims that for speakers of 200RMS the following specs of 65 W + 65 W (20 Hz - 20 kHz, 8 ohms,THD 0.07%)is fine. Even though Yamaha is higher powered at 100x2, Denon is better because it has high current capability and Yamaha has only standard power capability.
If you have fairly sensitive 8 ohm speakers (87 db or higher), either receiver should be fine. If you have 4 ohm speakers I would probably steer away from either, although from personal experience the mid to upper level Denon's can drive many fairly sensitive 4 ohm speakers.
If you have 8 ohm speakers that are easy to drive you should get the receiver with the features you prefer and the easiest remote and menu. Unless you have a separate universal remote, the receiver's remote and menu display will either be your best friend or worst enemy. For most people, using a receiver with a poor remote and dense menu's takes much of the joy out of the audio/video experience.
I have various neighbors that rarely do more than the most basic switchings because they are bewildered by dense menu's and difficult remotes.