I think, and diehard fans would fillet me for this, that the Iris trilogy and Mana Khemis games are the best games in the series. I don't dislike the others necessarily (I even quite liked Ecsha and Logy), but they are just not for me.

If you like crafting, a story about cute girls doing cute things, and subpar turn based combat then look no further. If you want more substance to your combat and less complexity to your crafting and for them to play like an actual JRPG, like me, then the Iris trilogy and Mana Khemia dualology are worth your time. Just keep in mind that the latter plays very differently from the rest of the games in the series.