the onkyo has 4 HDMI inputs, which may come in handy in the future.
on the other hand, the denon has the more advanced Audyssey MultEQ, which takes measurements at 6 room positions vs. 2 positions for onkyo's 2EQ. not sure how much difference this would actually make
either one is a solid choice. the denon with the coupon will be a bit cheaper.