I heard the forums recently re-opened and decided to join. Technically, I've been a fan of Osamu Tezuka ever since I went to a Tezuka exhibit at San Francisco's Asian Art Museum in 2007, but it wasn't until 3 years ago that I really began reading his manga avidly and branching out to titles not (yet!) available in English.
I have yet to read a manga by Tezuka that I didn't enjoy in one way or another, but my absolute favorites are Nanairo Inko/Rainbow Parakeet and Hidamari no Ki/Tezuka's Ancestor Dr. Ryoan. It would be fun to discuss these series at one point or another.