The 508 is the clear winner when it comes to features. You might be able to do 9.1 with the 508 (I think), while the 467 is strictly 5.1.
The 467 has YPAO, while the 508 has 2EQ. The 2EQ has more measurement positions (YPAO only has one), but YPAO can do more precise equalization in many cases. YPAO's filters are spread by frequency (7-band parametric per channel in older/lower designs, and 10-band parametric per channel and 2 sub bands for newer designs), while 2EQ does a rougher equalization on your speakers afaik (and does not do sub equalization). I'd slightly favor the 467 in terms of processing (we all have our own preferences).
In terms of power and current capacity, I think the 508 has a beefier tranny and discrete circuitry. So if you have relatively hard to drive speakers, the 508 will likely do better.
In terms of sound, the Onkyo has a snappier and livelier nature while the Yamaha has a more fluid sound with a fuller-sounding midrange. It's still best to listen to them with your speakers.