Go With Yamaha
I currently have the RX-V1400. I have had Onkyo receivers and CD players in the past and they died after a couple of years. I do not know what current Onkyo products are like in terms of reliability. You can download the Yamaha manual from their web site, Onkyo does not have the 801 manual on line. But just looking at whats available:
Onkyo does not up convert composite and S video to component, Yamaha does.
The Onkyo lists 20 more watts per channel. Not all channels driven for either unit - small point.
You can connect more speakers to the Yamaha (12) than the Onkyo (8)
The Yamaha has greater expandibility in terms on inputs and outputs with discrete CD recorder and DVD recorder outputs (both analog and digital)
Onkyo has discrete 8 channel inputs form a seperate outboard DAC, Yamaha has 8 too, but only 6 discrete (for the other two, you have the use the DVD input for the front R&L).
Onkyo has 8 channel pre-outs, Yamaha only has 6 channel preouts.
So, whats important to you?