Donny, according to a survey conducted last summer by Bonner Music, the list is as follows:
Yamaha PSR-S970. ...
Roland E-A7. ...
Korg PA900. ...
Korg PA300.
Korg PA4X. ...
Now, other surveys put the Casio CTK-1500 at the top of the list, so when it comes to actual sales, Korg has a long way to climb in order to even catch up to Yamaha and Casio. And, as diverse as Yamaha is in the world of musical instruments, I really don't think they're even a little bit worried. Granted, Korg makes a great arranger keyboard with some really neat features, but when it comes to overall sales numbers, they are still near the bottom of the list.
All the best,
Gary