I don't think either is "better", because like you say, they're so different. Debussy was certainly the more progessive, inventive, atmospheric. Yet Rach so brilliantly seemed to tie up all the loose ends of the Russian Nationalists. Oddly enough though, at least for me, despite the enormous output each of them created, I listen to a fairly small part of each of their works. For Rach it's essentially the symphonies and symphonic poems, piano concertos 2,3 and Paganini, and ocassionally the operas. For Debussy it's the orchestral music, the opera, and that's it. I know only a bit of each composers' piano music -- which is what they're famous for! And I don't care for the chamber music of either. I also should say that the reason that I voted for Rach is simple: the Second Symphony. One of my desert isle disks.