I think it's funny when people say something ripped off of Star Wars because Star Wars itself is hardly innovative in most any way. The whole plot follows a very formulaic model and lends little originality in the way of story-telling in the first place.
FFXII has a remarkable amount of depth to its plot. It's too bad that it gets hidden behind characters like Vaan who forcibly take center stage when they really have no business whatsoever being there.
Edit: I'd also argue that Basch is more of a leading character than Ashe. The beginning and end of the game both tend to focus on his circumstance more so than any other. Ashe is merely a means by which Basch can redeem himself.