For less stat heavy RPGs, I'm sure Ys was the first for Turbo, seeing as it came with the Duo. As a young robot of limited means, I didn't have a ton of games early on, but eventually added Ys 3, Dragon Slayer, Order of the Griffon, Theron's Quest, and the aforementioned M&M3.
Prior to the Duo, it would've been the Final Fantasy games on GB.