FluidR3 is more neutral; Arachno is louder. Black Tyros sits in the middle—it has the commercial "polish" of a hardware keyboard.
To ensure you are using the actual exclusive version (and not a clone), check for these specific patches: black tyros gm soundfont free download exclusive
For those who cannot locate the archive, some developers have released the "Tyros Light GM" with a Black skin. However, for the exclusive experience with the "Concert Grand" and "Jazz Organ" presets, continue searching for version "Black Tyros XG v3." FluidR3 is more neutral; Arachno is louder