I have owned most of the Rolands, most of the Yamahas, several Ketrons, including Audya and Korg PA3x. I can use any of them just fine.
Drum and bass-wise, I would rate them Audya, BK7m, PA3x, PSR950.
When it comes to lead sounds it's a little different. Yamaha, Audya, BK7m, PA3x, more or less in that order. It's nothing etched in stone as everyone's taste is different.
Control-wise, Audya and PA3x are really close, with all the buttons, sliders, pedals, etc. The others lag behind.
They are all great. As T.G. Shepherd said: "Big, little or short or tall, wish could have kept 'em all, MMMM I loved them every one!"
DonM