You will never ... EVER get the answer to that question. There is just NO way to award anything that prestigeous title.
My preferences?
Yamaha 9kpro, , Roland VA7/76, Ketron SD1
I hate the kn series, and the Korg stuff is weak too.

Others will surely chime in, but piano tone is WAAAAAAY too subjective. Just like the acoustic world. Some like Steinway's ... some like Baldwins .... whatever floats your boat. I've played more Yamaha acouctics that I prefer to the Steinways I've played, but I've also played some killer Steinways and Shimmels that make you weep. It's a very personal, isolated issue and tastes change.