They're all so varied it's easy to fall in love with at least one. I personally love Nightmare Painter's and Silence's. The dark world with cyan and magenta highlights of Painter's world does something special in my brain and I dig the hell out of it. If I were to make an animation out of the book all of his parts would be in B/W with the hione lines being their colors and possible casting a colored glow on and otherwise B/W world. The creepy horror feel of Silence's is a fun, very tense divergence from the usual.
As much as I consider the first trilogy one of his weaker series mist born would have to be mine. The idea of flying through the mists with tassels trailing you is just a cool look to me.
Lumar; spores are wild man, and a whole bunch of them hovering above the planet with different colors all with different effects and them essentially acting like an ocean? Wild man. That whole planet sounds wiiiiillldd.