The Yamaha's component bandwidth is 60hz, I don't know what the Onkyo's is. If I was in your shoes, I'd choose between the Yammy and the Onkyo. They just give you more than the Denon. More inputs, front panel digital inputs (for xbox or ps2), better remotes, and so on. Altough the Denon does have 7 channels. I personally have the Yamaha rx-v1200.
I'm voting for the 2200, but I'm a diehard Yamaha fan. Truthfully, I haven't even looked at anything else. I am just trying to decide whether the 1200 or 2200 is the right option for my living room. I'm leaning towards the 1200 at this point as I'm planning on getting a pair of LeAmps to power the mains.