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?