Which photos shows the right way to train vines once they reach the top?
Note: grape vines have alternate branches.
Personally, I would prefer #1. It is more natural (less work) to have branches on both side, and it will be more balanced (shadow under the pergola).
But I would not worry much about the two possibilities. Every year you can change. The dark green is the branches of last year (and so you should move them to the right direction). The perpendicular branches are the branches that will growth during spring.