I'm a big Denon fan. I've owned several and have been happy with all of them. I currently have two 15xx and just sold a 19xx.
For the extra money, I'd step up into the 1613. You will get some extra features over the 15xx.
There are a lot of folks around here that are quite happy with their Onkyos, and I think you will get some extra features there. However, for my money, I'll take a little bit of extra quality in the Denon.
Nothing in this world will tick you off more than seeing a vegetarian eating pudding.