I'll try to be more articulated:
1- Jazz-swing: I liked more the S950 sax and the overall Yamaha sound is more polished, but here emerges the big problem with Yamaha: the styles have short loops (usually 4 bars long) and so after a while tend to become repetitive, even if they have live drums, like this one.
2- In the second song the Yamaha piano is more polished, but the Korg has definitely a different equalization and seems more distant. Even the Yamaha strings seem up front.
3- Wonderful tonight, or the big comeback by Korg: the PA-900 has definitely more punch and sounds like a live recording, while the S950 seems more like a studio recording and the overall sound is kind of aseptic, by comparison.
4- Classical: I was expecting a better performance by Yamaha, but was pleasantly surprised by Korg.
5- Country: Korg wins again; same considerations as in Wonderful tonight.
6- Blues: listen to the Korg bass and tell me if you can keep your foot from tapping; the rhythm section is much more like the "real thing", and the same goes for the harmonica and the electric guitar. Overall, I would say that the Korg sounds like a band from the Chicago ghetto and the Yamaha like a band of high school white boys trying to play the blues.
So, in the end the choice is -like always- subjective: do you prefer "Tutti frutti" sung by Little Richard or Pat Boone? Do you prefer the Art Blakey's Jazz Messengers or the Modern Jazz Quartet?