I have the Onkyo 502 and I would recommend it. Can't say anything good or bad against the others, other than I would choose the pioneer over the sony sight unseen (had 1 prior Sony when I first got out of college and Sony does not compare to others in the low end price range for receivers).
The 502 is 75wch, supports all the latest formats including pliix and dts 24/96, adjustable crossover between 60-150hz, adjustable speaker distances for all speakers, an easy to use menu system for setup accessible from the front panel or remote (no Onscreen Display), 3 optical in, 1 coax digital in.
The only thing it lacks is pre-outs and video upconversion. I don't think you'll find those features in any receiver around $300.
I've had it for a few months now and it has performed flawlessly.