Perranporth is the craziest I've seen, although I'd guess Jeff Warne and Clyde Johnson have some lesser-known contenders.
The next 5 (alphabetically):
Carne
Cashen @ Ballybunion
Cullen
Pennard
Prestwick
HM: Waverly in NZ
It's hard to beat Perranporth, it has the undulation
and the elevation change!
Otway (prior to the loss of holes) probably had the craziest, most compact routing.
Iona is crazy for it's rawness, and some wacky rock outcroppings that influence play. (Cullen is in the same category I guess, but way more refined.)
Barra is a hybrid of links and boggier ground, but that tackles some fairly crazy ground.
Those three would really get me going!!
[I'm not sure it's crazy, and it only has two links holes, but St Medan's - Scotland's most southerly course - is a recent 'find', full of cool half-par holes (including one of the best I have seen anywhere)!]
It's funny, most of the truly crazy golf (at least in GB&I) is to be found inland.