Heh! I thought such a reply would ensue.
LOL!
Well, frankly the reason I would put Gotham Knight above Mask of The Phantasm is because, since I watched the heck out of Mask of The Phantasm as a kid, it doesn't have the "freshness" that I feel Gotham Knight or the others have when I watch them. I really love Gotham Knight as "Batman: Black White"-type short stories.