After beginning to re-watch it recently Mobile Suit Gundam Wing stands out because of the character development throughout the series. As the political tides change so do the actors and their affiliations. Plus giant robots fighting is just cool.
The Gundam Pilots rebel against the Earth's control of their space colonies and in doing so change the political structure of the world very drastically. As the plot progresses certain key enemies fall into grey areas, and their affiliations are dynamic and unsettled by the Gundams and their pilots. The Gundams almost bring out their true colors.
In my younger days watching the show I found Gundams to be completely badass. Particularly the ones from this series. I mean, look at them:
Yeah, I know... (In case you didn't notice one of them is basically the fucking grim reaper).
But aside from the sick robots that these dudes pilot I've realized that what makes them badass is that they just don't give a fuck. They represent a group of people that don't even support them (so they have no real home), most (if not all) of their family members are dead, and they fight for a rebel cause that consists of themselves and the engineers that made the Gundams. Their basic purpose is to annihilate everything in their way and strike terror into the hearts of the oppressive, tyrannical regime on Earth. They fuck shit up. And they do all of this with complete disregard for their own lives.