Better late than never.
The 135 f2 would be my weapon of choice. Stopped down to between f4 and f8.
Second and not far behind would be the Sigma 150 or 180 Macros. These are totally underrated lenses, and while their AF is very slow compared to Canon's they lack nothing in sharpness or clarity. In fact Sigma's 180 is arguabley sharper than the Canon 180 at twice the price. They never hang around long on the B&S forums.
In joint second would be the 200 2.8 Canon L along with the preposterously awesome and unequalled Canon 300mm 2.8L. Well maybe the f4 version also.
Nothing like primes for AP IMHO.