I dont get most of those comments on youtube... people declaring one or the other a winner.

Isnīt it obvious that you canīt compare both, Korg sounds are much cleaner while Yamaha sounds come standard with a little effect and reverb, making them sound better. But then with some effort and use of the effects section this can also be done on the Korg.

Both instruments sound good... Yamaha is better for people that just want to select sounds and play them, tough the more creative musician might enjoy Korg more.
Yamaha Genos, Roland Jupiter 80, Ipad pro.