Well, I'm just saying that when someone singles out a composer as the "best", they are (usually) pointing out their favorite. Mine is Brahms, in terms of overall completeness ... I hope that doesn't make people think I'm boring :p
Two things. There is almost never a "best" at anything, anywhere. A more appropriate thread title would be "who is your favorite composer". Second, many standard definitions of the "classical" period (at least that I've heard) extend it up to Beethoven's death. But why ...