I agree with Learsfool about the value of 'best' lists. Silly and at best fun. Ultimately, in most audio forums anyway, it is a value assigned with no foundation beyond which composer's music impresses that person at that particular time.
The alternative selection criteria for the 'best' could be (and I think should be) based on not only the popularity of the music but, maybe more importantly, the composers contribution to to the evolution of music.
For example, while I don't listen to Bach's music much, his contibution to the developement of music was huge. Wagner, another who introduced a form completely different from that which preceeded him and influenced subsequent composers, maybe not as huge as Bach, but I like Wagner music more. Beethoven is probably the most influential of all balancing both innovation and popularity (then and now). His music for me is just facinating and has been lasting.
The list which started this thread was, no matter how much you may agree with the selections, at least one in which the rational for the selections was set forth and could be the basis for some lively discussions. Not so much for most of the opinions contained in this thread I think.
Because it is so personal, I think, I will not contribute to the list. Who really cares what I like. But I must admit I have found it facinating to see who others have placed on thier lists. So far I've resisted challenging them. Visualize a halo over my head! :-)