The best composers are both. Beethoven immediately comes to mind because his compositions are both--how can I explain this?--regular, meaning you can listen to one of his pieces and almost predict what will happen. That's the rational part; I want to characterize him as mathematical, almost. However, he never lapses into tedium or true predictability because he can articulate through sound the entire range of human emotions, whatever they may be, in the most perfect way. Put simply, he can make you weep.

Now, at times, Shostakovich makes me nervous because sometimes his pieces go in too many directions at once, so in my mind, he tends to be more emotional rather than orderly. This isn't to undermine his genius, but as I said, my mind loves order.

So naturally, if you've ever heard Phillip Glass's composition for Koyanisquatsi, it nearly drove me crazy. Perhaps because it's so minimalist.