I would say that welded diff is better because it is easier for the typical do-it-yourselfer to do than the aluminum or lead diff. Some say that welding weakens the gears, yet I have not heard of and welded diff ever failing. Maybe because of a poor welding, but until someone shows me pictures of a broken welded diff I am sticking with it.
I would be interested in learning how to perform the aluminum/lead diff and wish someone would do a write up on it with pictures.
87' Samurai/1.6L/dual 40mm Mikunis/header/2" exhaust/MSD 6AL/5.5" SPOA/1" shackle lift/CJ-5/Sami springs/31" High-Tecs/roll cage, bumpers & pumpkin caps in progress...