I'm a fan of all my fellow MOCers. But my overall favorite has got to be @Djokson. His ingenious use of random Lego parts to construct those wonderful characters from his imagination is truly astounding to me. Like, how does a person's brain work that way? It's real art.
After that, @Jayfa, @LoganMcOwen, and @ReeseEH are also really great. I'm sure I have other favorites too, but those are the ones I can think of off the top of my head.