PC is still my favorite, but he has written a number of really good novels, and his short fiction is also fantastic. Many people seem to like Diaspora even more -- may just be a matter of taste. My love of PC is probably more due to the subject matter (CA's as the underpinning of physics) than due to the book itself being better as literature than his other writing. Like most SF writers, I have a hard time actually remembering his characters -- they are there primarily to present his themes.
If you want a novelist who writes SF but actually creates 3D, memorable characters, try Walter Jon Williams (Aristoi, Metropolitan, Implied Spaces... but avoid his serials IMSHO)
