Richard Wright is a composer of outstanding ability. I can think of very few other writers that can come up with chord progressions that can conjure such an incredible sense of mood and colour. Let's not forget that "Us And Them" is his music and is one of the greatest pieces of music ever written! Anyways, his harmonies with Dave are tops.
Rick's definately my favorite (after Syd of course, but that's a different story and a different band).
-Chris