As much as I like the Game Gear, it's not especially sexy. The Lynx model 2 and the Turbo Express both have it beat in that department.
The Gameboy Color was nicer than it's predecessor, but not really sexy. but anything would look sexy when your only competition, in the late 90s, was the Game.com.
The Wonderswan was pretty, and the WSC made it even better. By comparison, the NGPC was kinda clunky. (but oh, that clicky stick.)
The Gameboy Advance SP was pretty nice looking, as is the DSLite. The Original DS and Advance were not so nice. The Gameboy Micro was nice, but not as nice as a fashion accessory should have been.