Jane,
If you have been reading these posts you know that there are alot of opinions as to which is the best. If you are coming from the i3 and it's the styles you are mostly interested in, I'm surprised you are not also adding the Solton X1 in your options. In my opinion, the X1 is still tops in styles, followed by the 9000pro and the PA80 tied for second. The Yamaha and the Korg are both very different. The Korg has very good styles but you might find them to similar to your i3 (as all Korg i series keyboards have very similar styles) and you might find the Yamaha styles a little bland after playing Korg. All in all, it's the Solton styles that my customers prefer. If I had to choose between the two you mention, you will find the yamaha much easier to use. The button pushing to get to style, sounds, effects, etc. is much more user friendly than the Korg, but then the Korg is much less expensive. If you need a really good feeling keyboard with 76 keys go for the Yamaha. My first choice...........Solton X1.
George Kaye