So here are mine.

Favorite Fujiko design: 1971 series
I've never actually seen the original series, but I love the vintage look of this character design that's very representative of the early 1970's.

Favorite Goemon design: 2nd series
Some of the other character designs make his face real thin or bean shaped, which looks really ugly. I prefer the simple, oval shape of this design that makes him look appropriately somber and serious.

Favorite Zenigata design: Castle of Cagliostro
Most designs of Zenigata just make him look silly but Miyazaki's more realistic, stronger looking Zenigata really befits the more admiral than usual role he plays in this movie.
Jigen never changes that much.
And of course...

Can't beat the orginal.