As @Peter48 writes, it really doesn’t matter. In fact in the UK, they zig-zag the wire, which I really like as it doesn’t affect the queen’s laying pattern as much. There is a photo here, if you want to see what i mean:
Fishing line works brilliantly, you just can’t melt it into the foundation. It still holds the foundation well, and once the bees attach the was to the top of the frame, it is very solid. Fishing line is also a bit easier to handle than wire - easier to thread, cut and knot in place tightly.