What is "best" is totally subjective. The Korg is "best" for me. Operating features, live sounding styles, vocal processor/harmonizer.
If you prefer Genos, that's wonderful, but you really can't tell everyone it is "best". Well I guess you can, but that doesn't make it valid.
I can see where Ketron is "best" for many. The Genos would be my third choice at this point, even if all were priced sensibly.
with only 4 TOTL "arranger" kb contenders makes it very limited in choices these day,....all 4 are capable,....but there are also other avenues to create music if you open your mind. But as Don said if you a Singer/player the KORG Pa4x and soon to be Pa5x is hard to beat for live performance in so many ways.