Hi Sxpoet, it all depends on the person playing. I prefer the darker MP’s too and when I play in our group, my wife says that my tone is much darker and richer than the chaps playing on the Tenors. I’m still learning, but thanks to my longer practice hours I can now produce a better tone with my alto. It all depends on what type of music one is going to play I suppose. Equipment is important, but as Johnny has recommended long-tone practice is the way to a richer tone.
Regarding Soprano, its become clear in discussions that the Soprano’s sound tends to irritate some people, when played an octave above the normal vocal range.