The Turbo has a lot of platformers, but almost all of them look like Mugen hacks of each other. Very few have a post-Super Mario Brothers 3 level of sophistication (or even post-Super Mario USA for that matter). There is nothing like Castle of Illusion, Yoshi's Island. f*ck, even Bubsy looks like Virtua Fighter 3 compared to Turbo platformers. That genre just rotted on the vine. Right when platformers went in a new direction on other systems they were pretty much abandoned on Turbo. I think most are pre-1990, aren't they?
I'm going to go with Bonk 2, especially if imports and Dracula X/Ninja Spirit don't count. If imports count, Blue Blink. If Ninja Spirit counts, I'll go with that. If Drac X counts, it's Drac X. No question.