When I was growing up (in the 1940s and 50s), "fuck" would have definitely been at the top of the list. Nothing else even came close. Today, through over use, it's much less powerful, and I would see it in a rough tie with "cunt" and "shit".

"Crap" would be next, but at a much less powerful level, with "hell" not far behind." My 84 year-old aunt would drop either of these into conversation with family and friends.

"Heck" seems much more designed for adults to use in the presence of young children. But only if they are being self-consciously "virtuous." It carries nearly no power, except as a euphemism for "hell."

"Bloody" and "bollocks" have no power on this side of the pond.

There is no word I hate more then 'cunt', followed by fuck, everything else... it's meh

Crap is actually a noun (or part there of)