LOL, what a loaded question. it really depends on what you want out of the forum. in general the pep's on JC are probably the most helpful (but there are some real know it all buggers on here
)
AussieV8's is another good site for Holden V8 stuff (although not a commodore forum a such).
SC is fine but seems to be more about "mine is bigger then yours" and you'd better keep your head down if you drive a V6 (buick/ecotec) and still use a delco PCM LOL