The only 16-bit RPGs I've really enjoyed are Mario RPG and Chrono Trigger. My favorite JRPGs on the PS1 were FF7 and Grandia. I'm not the biggest JRPG fan, but I was hoping to find something I genuinely enjoy. Although I did complete Final Fantasy 1 & 2 on my DS. That was fun.
Are you sure you've given a large enough look? There's an awful lot of RPGs on the DS, and so many are very different from one another. I mean based on what you say you've enjoyed in the past, I'd recommend:
Mario and Luigi: Partners in Time
Mario and Luigi: Bowser's Inside Story
Black Sigil: Blade of the Exiled
Dragon Quest V: Hand of the Heavenly Bride
Final Fantasy III
Final Fantasy IV (If you hadn't played this on the SNES previously)
It's hard to give you recommendations without knowing what you've played already, but I'm very knowledgeable about many of the DS' RPGs so I could give a helping hand if you're still willing to try some out.