I would have to say that Gundam Wing is better. I watched Gundam Seed and I was actually bored with a number of the
episodes. A previous post mentioned that it was because Wing focused more on the political aspects of war - maybe that
was what endeared Gundam Wing to me. The suspense and behind-the-scenes intrigue always had me coming back for more.
It had a hands-down incredible plot, with just enough emotion as to not make it an angst-fest or have continual
screaming for whatever reasons. And the characters (along with their relations with each other, differing
personalities, and towards their roles in the war) were awesome. And some good humor as well.
If put in terms of animation quality and the like, Seed exceeds it. Though this probably has more to do with the fact
that Wing came out years ago, way before Seed, and animation has come a long way in such a short amount of time. But I
don't believe Seed can hold a candle to Wing's plot and premise.