I think the advice from
@Astro14 is sound. But if you still would feel better having fluid on hand, I would go with the Dexron III, simply because of availability.
Based upon my experience, trying to find ISO32 for my motor home power steering system, it can be tricky to find. ISO46 is similarly tricky to find, unless you have tractor or HD trucking supply stores in your area. Dexron III compliant ATF is everywhere, including likely already on your garage shelf. And if it's not, you can wait until you need it, and pick it up at your convenience.