well, since taste is subjective and you're looking for an objective measure, I'm just going to judge on other grounds! I suspect that the vanilla industry is less bad for the environment and has a better track record with labor violations, so vanilla is better.
Now, I didn't research that first, and I could definitely be wrong... but at least it's something one can actually be wrong about.
I dislike drinking/eating vanilla on it's own. I like drinking/eating chocolate.
I don't know why this was downvoted so much. It's an honest question. But anyways, I'll go for chocolate because chocolate can go with mint.
vanilla is a lot more versatile in my day to day life. Of the two id say chocolate would be less jarring if it disappeared from my life.
I'm gonna go chocolate. Certain things I prefer vanilla though. Like vanilla fudge is the shit. But ice cream I'm going chocolate.