Ground Strap vs. Ground Cable

Yeah, seems like some discussion on different things here.

For the head to firewall, the flat braid is most common in my experience, but either works fine electrically. Flexing is the thing to consider there, since the length is ususally short. I have seen some older Jap cars with a small group of paralleled insulated wires and crimped into the same lug for a flexible ground.

For the main ground wire, the large stranded wire is the common thing. But, I have used large flat braid for that on a race car for many years with fine results. For DC and low frequency, the electrons do not care.