<font color='#000000'>Loaded question...
If you like Yamaha sound and soundfields (like 70mm cinema), the RX-V800 is nice, but only 5.1, and no HDTV component switching.
Denon is nice, with modern sound field decoders, 6.1 and HDTV component video switching.
Outlaw box has no component video switching, if you want that... many people hook directly into their monitors.A big selling point for this receiver is its variable crossover setting...
No opinion on the Onkyo as I haven't heard it. Its big brother sounds pretty good.
I try to listen to as many as possible, on the same speakers if you can. Sometimes this can be arranged, and sometimes it cannot. I am a fan of Yamaha's upper lines personally, but there are other amps here with more features than the 800 that are highly rated as well. I would have to seriously consider those other options.
Also consider whether you want component switching and if you plan to use a rear center speaker.</font>