South of Heaven isn't bad but it's miles ahead of Metallica's self entitled which, contrary to popular opinion, I honestly don't think is too bad. South of Heaven is much better, though.
I think Metallica is by far the best of the four; their songs vary a lot more than any of the other three banRAB'. Metallica can pull off power ballaRAB as well as thrash metal anthems, whereas the other three can only do the latter. This was made pretty clear in the Big Four concert broadcast.