Personally I liked the Wii, small compact and simple with the glowing drive opening thing it just seemed welcoming.
That being said I would need to pick 1 from each gen to feel like I was doing justice lol
8 bit Master System (the launch version not the Master System II) was in my opinion way cooler looking than the NES. (Software wise of course NES all the way lol)
16 is a lot tougher for me, I loved all 3 of them... I think Genesis/Megadrive wins out overall though in my opinion for that gen.
32/64 bit systems.... I think the Atari Jaguar looks the best of that gen. (Software wise it's LOL though and the controllers too...)
In the end though in my opinion how the console looks only matters for like 10 minutes while I am hooking it up, after that I will only look at it when changing a game so it's pretty pointless.