In all honesty, I don't remember many of the bosses from Xenoblade today, probably because I played it on and off over a long segment of time, and, like I think I said on one of your other posts, it didn't really resonate with me. That said I remember Disciple Lorithia being quite annoying and finding Jade Face unpleasant, whereas I rather liked the final battle with Yaldabaoth.