You found me out! I realize how many fantastic Bach works I left out; trust me, Johann Sebastian is very highly regarded by me. I'm overall quite a "fan" of his work. It's just that the other composers mentioned above (especially Mozart) just tend to seem less mathematical on the average (hey! A bit incongruous, that sentence, "mathematical, average").
Allow me to pick up on this, being a discussion board and all...
As far as the 'mathematical' thing, I can see where it's easy to think this. Bach is, after all, a master of proportion.
But to me getting under the skin of the music, so to speak, is where I find the greatest musical rewards. The felicities deeply buried under all that surface structure (mathematics) is where the gold lies in Bach.
And the imagination on display underneath the mathematical template to me couldn't be more pliable. Not to mention colorful. IOW, it'll put the boogie-woogie in your step! Contradictory this may sound but that's the nature of a genius.
And yes, I'd agree it's the vocal music (cantatas, Passions, etc...) where this is most in evidence (and his greatest music).