Gotta say recently I've been very impressed by the music from some Nintendo DS RPG.
Etryan Odyssey III has one of the best selection of musics I've heard in a video game in a long time : http://www.youtube.com/user/Banim#grid/user/52C40159A7DDB8FA Excellent variety of tracks, somewhat old school sounding yet modern at the same time, always perfectly adapted to the situation

It's older siblings soundtracks are just as good too.
Radiant Historia is a less well known RPG on the Nintendo DS and is IMHO one of the only good jRPG in those last years. It also sports an awesome soundtrack : http://www.youtube.com/view_play_list?p=E169075E540F2C3B The main battle music by itself would manage to help us pass through the fights without getting bored : http://www.youtube.com/watch?v=nzQq3-9nhKA&list=PLE169075E540F2C3B&index=4&feature=plpp_video

And on a very differently sounding register, the Shin Megami Tensei games got such an awesome soundtrack! Here's a playlist for the "Strange Journey" spinoff on the Nintendo DS (again ^^) http://www.youtube.com/watch?v=NLQUxXrucW8&feature=results_main&playnext=1&list=PL6F462945A13FB506
Brb, checking Atlus site for news on the next RPGs and RPG like games they are making XD