As to what's a better build tool, I don't know. I would be very careful about switching away from what the developers know, though. How is switching going to make the team more efficient? Is the benefit going to be worth the disruption?
Re: Ant and XML. I've never quite understood all the hype about XML for applications like this either. It seems to me that having the editor do syntax highlighting of keywords, etc., takes care of the readability that XML provides without all of the extra baggage.
Luck!
Cheers,
Scott.