That's a hard question... I'd go for either marshmallow, funky banana, Kinder chocolate, candyfloss or birthday cake, but I can't pick between them.
Edit: I forgot about cherry pie and custard, that'd have to be a contender too.
im super basic so i like anything that involves chocolate or vanilla
chocopolitan is good because it has chocolate and vanilla, and it swaps out strawberry for choc chip which is also great (although i dont mind strawberry ice cream either)