Possibly none of them. The stud on the late S2a and EC and EC-TL doesn't quite match anything else. I wouldn't buy anything you couldn't try first. I believe there may be an RB-67 strap that might work.
Get the pro or pro loop version (with the loop through attachment). Bronica has the two small rings so this should work fine, and has for me.
(No lugs like for a hassy)
Mine is an ETRSi so not sure on the EC...if it has rings, these will work.