I've owned Ketron products before and found them to be awesome in tone, but out of the norm in design and service. It's true - demos of both sound amazing, but I would place more trust in the track record of Korg than I would in Ketron. I have used Korg products for over 30 years, and found them to be ultra reliable and musical. There is no "best fit" for everyone, but you asked for advice, and that's the best I can give.
Some of my best recordings are from my X-1, but there were always issues with comfort. For me - Korg has the best package for what I need most:
Let's face it - all the high end stuff has great sounds & styles, but I need more:

*Powerful monitor speakers that handle my vocals well
*Super harmony with the onboard TC unit
*Flexible playback options for SMF/MP3/Live

Korg gives me all three. When someone does it better - I'll listen.