Anything by Bach and Mozart, greatest musicians who ever lived beyond all doubt .
It must be true because I cannot imagine to contest it with my own preference, for example in the case of Mozart...Because my preference will appear precisely like that: only my preference....
I think it is a fact, Bach and Mozart gives to their music some "constant" high level of perfect form/emotion ratio and this was never really surpassed, on these 2 counts, by any other composer to this day...
The last factor would be the sheer astounding numbers of opus with these 2 factors in them....