The similar topic in another part of this forum got me thinking about the best fight scenes in general in anime. Since there are enough of them, I figure this should be a fairly easy topic to contribute to.
Feel free to embed or link videos as necessary.
As another member here pointed out to me, the opening gun fight in Canaan was pretty damn good too. Doesn't look like there's a youtube clip of just that.
I'll add more if I can find 'em and someone else doesn't add them before me.