I think it's pretty safe to put Bach, Beethoven and Mozart as the top three, far and away--and forget about rating them against one another.
I personally would list Baroque stalwarts such as Handel, D. Scarlatti and Telemann up there with many of the "also-ran" great composers of later years who seem to get mentioned.
I personally would list Baroque stalwarts such as Handel, D. Scarlatti and Telemann up there with many of the "also-ran" great composers of later years who seem to get mentioned.