I know there have been many iterations of the Gundam series, but for me Gundam Wing will always be the top. Maybe it's partly due to the fact that it is one of the first anime series that I ever watched, sitting together with my best friends in our college apartment in time for Cartoon Network's Toonami, but I think it's largely because of its quality, characters, riveting story lines and great action. It's also one of the few anime series that I bought for myself (complete anime series can be very pricey, as you probably have found!). I got super lucky when it magically appeared in the movie shelves of my favorite used bookstore - so naturally I snatched the box set right up!
The show's full title is Mobile Suit Gundam Wing, and it is a mecha anime that revolves around a war between Earth and its colonies in a scifi future in which the human race has divided and colonized other worlds in space. The nations of the Earth have formed a powerful Alliance, the leaders of which are using their united military force to oppress the people of the colonies. After the colonies' pacifist leader is assassinated, a group of scientists mount a revolt, develop mobile suits to fight against the Alliance forces, and recruit five teenage boys to pilot these "Gundam" suits.
The characters and individual story lines are extremely well-developed. Each pilot has his own origin story and comes from a different nationality. Their unique qualities and stories are reflected in the unique aspects of each suit assigned to them. The other characters on both sides of the conflict are also very well-developed. The story line is a very complex exploration of war, pacifism, politics and the entangling of personal relationships with ideological pursuits. I also like that there is no simple "good" and "evil" separation, but rather the different motivations and conflicts on both sides come forward at different times. The tone is not humorous - which sometimes I really like. The story is enjoyable, but generally serious and dramatic. It's also a fabulous example of a space opera - with magnificent, epic battle sequences throughout. Plus, the animation is beautiful, the suit designs are very cool (as we know from other Gundam series and the many stores exclusively dedicated to the models), and the character and outfit designs are pretty awesome.
I highly recommend Gundam Wing! I've watched it many times and am planning to start again soon.