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)
I do like rainbow sherbet, vanilla, cheesecake, rocky road, cookie dough, Neapolitan (though if I can omit chocolate, I'll like it more), cotton candy, bubblegum, and birthday cake
Cookies and cream is my primary choice, and I am partial with those with a rich chocolate flavour too. I think those with fruits mixed in the ice cream is also a delight.
That's what's so great about it! It's yummy on its own, but you can also add pretty much whatever you want to make it even better. Vanilla doesn't clash with much.