How can there be a choice between the two! Without a product, what are you investing in and without a vision, why are you investing in it!
I mean which one is more important, not choosing one of them. They are one of 4 standards to review an ICO project - can not postpone any of them.
I'd suggest to pay more attention to product:
1)Is there demo/MVP?
2)roadmap for development of product itself.
3)is all described is possible to implement?
It seems we are actually missing the point here. The second thing you mentioned is what? Do you think there would be a road map if there is no set out goal or vision? Even if we keep going back and forth, they are both necessary. As long as you are leaving the other for one, it is more like you are trying to play a game of luck in your investment.
Based on the question, I personally care about the two of them and if one is absent, I would rather skip and see how the project sets out in the market in the long run.