Ian, sounds (tones) are SSSOOOOO personal..What I like another will not..what you like, some one else will not....What we are use to..is also what we "think" sounds better..

Most Yamaha owners marvel over the "mega" tones....I think when compared to the standard XG tone bank...sure they stand out...but compared to other brands that have similar tones..the other brands equal or sound better....It is a individual taste...and there will always be heated arguments about what each of us think is the better sound..

As I mentioned over the years ..All manufacturers have sounds that "stand out" compared to the competition..

Personally, I thought the Yamaha concert guitar was a stand out...but less than excited about the other heralded tones..
I thought that Roland excelled in choir and scat voices..that were unmatched by the other brands...

I thought that Ketron's drums and bass over-matched the other brands...

But to endorse any instrument across the board as the best sounding keyboard...simply is not true...But, personally we need to choose what works overall for each of us...For some that may be Yamaha...and for many other folks..it will be another brand..