The Wii is just gorgeous - probably my favorite looking console of all time when in its stand. Second place would go to the NES; I love its look and the front loading design was just so cool and different from all of the top loading consoles back in the 70s/80s. Both look really great when placed together with their respective controllers as well. I also like the look of the Super Famicom and the Gamecube (provided we're not talking about the purple one).
The only Nintendo consoles that don't look good to me are the original Famicom and those second models of the NES, SNES and Wii.