Have you checked out etrian odyssey 3? You have to kill monsters to get their parts to sell and unlock gear. The only thing I hate about the game is it's extra grindtastic
but it's not that big an issue to me.
Rune Factory 3 is a good one if you like a blend of harvest moon.
Do you like tactical games (strategy?), Final Fantasy Advance 2 is good, not to mention a long game (I've netted over 400 hours into it and still haven't beaten the story
Digimon Dawn/Dusk has a lot of customization in the way you have different monster combos you can fight with
Phantasy Star Zero is a good hack n' slash
That's all I can think of off the top of my head, most everything else I've been playing are rereleases and turn-based dungeon crawls (there are way to many of those on the DS lol)