Going through this as well right now, I guess Burkhards Axle shafts and full spools have been pretty much unbreakable from what I've heard. But Haisleys 37 splines have just as good a reputation. You can fit a bigger shaft in a Dana 80.
Stock for Stock the AAM 11.5 is alot stouter. I dont know what kind of support there is for the GM 10.5" 14 bolt, John "dmaxlover" was telling me they have the same size shafts, the 10.5 has a supported pinion, but the 11.5" doesnt. I may try to make one live if I cant find a good deal on either a D80 or a 11.5 because 10.5" 14 bolts are dirt cheap and everywhere. I cant find a 11.5 for a decent price anywhere close.