The more I listen to Shimomura's works, the more I think she's one of the very best VGM composers. I imported "drammatica" about a month ago and I can't stop listening to it. By far the best arrange album I've heard so far. Fantastic, epic music.
My favourite Mitsuda work atm is the OST for Soma Bringer. Arc Rise Fantasia seems to be great as well (I received the CD box only yesterday), but according to the booklet he "only" composed 21 out of the 71 pieces (two small Shimomura compositions are on the ARF OST as well). As I really liked his Soma Bringer music, I recently ordered Xenogears and Xenosaga and hopefully will get them soon.
In short: Xenoblade is very high on my watchlist of this year's OST releases (along with The Last Story, Ninokuni, FFXIII and Nier).
ACE+ could probably have something to do with these guys: http://vgmdb.net/artist/6508 (just a guess).
