Favorites:

Jaguar - It's just nice and simple looking. Yeah, the CD add-on doesn't look so great but it's not terrible either.
Dreamcast - One of the best designs for a CD console.
N64

Least favorites:

Sega CD 2 - I always thought this version was just cheap looking.
Master System 1 - I dunno, I just cringe whenever I see it.
Gamecube with GB player add-on - I don't think it looks bad otherwise but ho boy, it just looks hella awkward with the add-on attached.