The Yamaha 5760. I've owned a few Denon receivers (AVR-1802, AVR-883). Yamaha makes a great performing and great sounding receiver for the money that the 5760 costs.
Denon is popular because it has a good following.
However, if you have a chance to listen to both receivers and see what features each offers, please do so. That is the best way to pick a receiver. I could be telling you all this great stuff about the 5760 and you could get it and think it sucks.
don't quote me, but i think the 1705 is low on the denon chain, while the 5760 is high on the yamaha chain. (i own the 5790 myself).
both receivers are solid choices. i've always liked denon's amps - they're always seemed rock solid. but if you're into dsp's at all, yammie is the way to go. they're the only receiver whose dsp modes i actually enjoy (and i'm not a dsp kind of guy).
ultimately i went with the yammie, but i got an employee discount -- so it was a no brainer.
again, both receivers are good choices. check them out and see which one has the *features* you want. which has more inputs, which has a nice remote, which one has an interface/display you like. ultimately those are the things you'll see and appreciate.
performance wise i bet they're both pretty close and it'll be tough to tell the difference anyway. i know i sure couldn't.