I'll just view excellent bass tone as something that fits the music. Ex: Billy Gould has excellent tone(s) and so does Mike Inez, but their tones (and approach to the instrument) are fairly different.
That said, I dig Matt Till's band King Bowman.
KB
Also, Ron Now's band Guaime.
Guaime
I believe this is the band of a TBer, but I can't remember his name.
Kidney Riddler