Mine is Lady Sia for GBA. It's just a platformer but I just love it played and completed more 20 times. Will probably speedrun it in future.
Legend of Dragoon was so good, even if several twists were the kind you see coming. And it was insanely long!
I wish it would get remade so badly. I own it, and tried to make it work, but I don't have a CRTV, so it went very badly.