I've always liked the simplicity of the original six robot masters. Especially compared to how crazy awesome some of the later bosses would get. The more down-to-earth style of the first set really does make them feel like the groundbreakers of the Robot Master technology, as well as helps highlight their initial industrial purposes.
Each sprite is still limited to five colors maximum. I've also touched up Megaman, Roll, and Cutman a bit.
Extended family to come later.
(Incidentally, I'm really sick of DA's policy on GIF thumbnails.)
Edit: I took another look at Iceman and Gutsman, and realized I got kind of lazy with their redraws. I based them too much off other version's sprites, and not the official art. so I rehauled the offending parts. I also touched up Elecman's head a bit.