After much consideration, I gotta go with Scary Monsters. It was my first Bowie album. Its got Fripp, its got mellotron, its even got Pete Townsend. I love the production. I really like the mix of arty wierdness and commerciality.
Scoff as you will, but back in the day I was surgerically attached to MTV because of people like Mr. Bowie. That's a big reason I like the album too.
Funny, I didn't think I liked Low that much but re-listening, it is pretty darn good. Lodger doesn't hold up as much as I'd like it to.
And the later blantently commercial stuff is still good. I can listen to Blue Jean all day long (well, maybe that's a little exageration). Earthling isn't half bad either.