I'm going to HAVE to recommend Final Fantasy IV. Its the best graphics on the DS, and its turnbased combat. The cutscenes are amazing.
However it's pretty hard and a little on the short side. I loved it, but i am ashamed to say i cheated on it.
I would recommend looking at some of the cutscenes. Here is the first one. Its amazing the cutscenes arent easy to find
http://www.youtube.com/watch?v=qqcdU0mLGmw&feature=PlayList&p=7217130B37D03856&index=0&playnext=1
Anyway hope that helps.