From what I have played, I would have to say that the best NGPC RPG's are "Densetsu no Ogre Battle Gaiden" and "Ni-Ge-Ron-Pa!" But, if you count "Dive Alert" and "Pocket Love if" as RPG's, then those too.
Ogre Battle is a wonderful strategy game. Great animation, challenge, and options.
Ni-Ge-Ron-Pa! is a classic-style RPG, and that's the main reason I like it. Its funny too! The characters look really cool.
Dive Alert is a pretty good game, but it takes lots of patience and time to get any enjoyment out of it. The most accurate submarine simulator that I have played (and also, the only one). Kinda reminds me of Armored Core, which I also love.
Pocket Love if...Quite possibly the best NGPC game ever made, I think...Hentai Dating Goodness!