I voted Blood Fire Death straight out of my guts. Really I should have gone back to these records before voting though. As the only Bathory records I have ever owned is Twilight of the Gods (which I think is so-so) and the Scandinavian Metal Attack compilations. For the rest I have had to rely on my brother's record collection which I haven't dug into very ofted during the last twenty odd years.
Onto my "to buy list", I guess. Along with the first three Slayer albums, most of Motörheads back catalogue, lotsa post mid-nineties Saxon and Scorpions stuff etc. etc.