Frys has brand new Onkyo ht-rc180's for $399, which is a good deal. I bought it at $499 and was happy. It does get hot, even at idle, so you'll want very good ventilation.
Refurb HK's at their ebay store offer a lot of bang for the buck as well. There had been some issues with hdmi, you may want to google for that.
Denon makes a good product, and have recently come out with a new line supporting 3d so there should be good deals to be had on the older models. The same is true for Marantz.
I wanted 4ohm stable amps when I was looking so I didn't look into Pioneer and Yamaha so I can't really comment.
As long as you pick one with the features you need I don't think you can really go wrong with any of them.