Personally, I've always liked Marantz and Denon receivers, though Yamaha also makes some fine sounding equipment. It would be helpful if I knew what kind of music/movies you typically listen to or watch, how loud you like things to be, and your budget. But I'll take a stab in the dark anyway.
I'd check out the Marantz SR-5600 or the Denon AVR-1906 (around $500 to $550); or if you can stretch the budget a bit more, the Marantz SR-6400 or Denon AVR-2106.
If you're looking for a unit that you'll be happy with for many years to come, you might even think about the Marantz SR-7400 or Denon AVR-3805. You can find them for under $800 right now, but they were originaly $1,200. If you really need to keep the cost down, then take a look at the Denon AVR-1706 ($400 to $425 if you look around), or the Marantz SR-4400, which can be found for even less.
You can also find some good deals on factory refurbished Marantz gear at
www.accessories4less.com
We're all biased in our opinions, bit I don't think you can go wrong with these two brands. I've owned Marantz in the past and was very happy with the product.