Is it better to freeze crepe batter or cooked crepes?
It is a compromise either way.  Neither will be as good as freshly made, but both methods will work.  As far as frozen batter, you will either need to plan ahead, or be willing to wait for it to thaw.  If you go this route, I would suggest zip style freezer bags, and freeze flat, so that it will thaw more quickly.  Also, some of the leavening power will be reduced.  So, if you enjoy fluffy pancakes, you might not be able to achieve that.  On the other hand, frozen pancakes are fine too.  However, you also lose some quality here as well.  The issue is reheating...unless you have a combi-oven, where you can use steam to bring them back to life.  In terms of length of storage, as long as they well packaged, the shelf life is about the same.