I am somewhat fascinated with FF Legend II as it was the only gameboy RPG I had as a kid. I am also annoyed we never got the DS remakes and hope a rom translation for them one days surfaces.
I also in general am fascinated by gameboy RPGs named final fantasy which were not entirely FF games. Mainly I include FF Adventure in this category. Final Fantasy Adventure is really a Seiken Densetsu/Mana game which had FF elements injected into it late in it’s dev cycle. The GBA remake Sword of Mana converted it back into a Secret of Mana game proper by former Secret of Mana devs working at Brownie Brown/Nintendo; though the recent modern HD remake seems to have swung the game back in the other direction.
What are you collecting? The GB/GBA are my favorite consoles ever, and ive been slowly amassing my own collection of games and dumping roms. Its still a meager collection but its growing into my own personal best of + always meant to play. Handheld game consoles are kinda my personal favorites.