For me:
1. Cowboys from hell
2. Vulgar display of power
3. Power metal
When "Far beyond driven" was released I bought it the first day and it meant a big dissapoint for me. In my opinion, that album is overrated. Nowadays I only like "Becoming" "5 minutes alone" and Black Sabbath cover from "Planet caravan".
Even I prefer "Reinventing the steel" ´cause I expected nothing from that album and it owns two or three very good tracks.