Opeth17 said:
I have "Rust in Peace" and "Countdown to Extinction" and like them both.
They pretty much exhausted themselves on Rust in Peace. I can recommend that you get everything prior to RiP with confidence. Even I need to get the debut (now that it's been finally remastered).
I'm going to take advantage of BMG's "I'll give you twelve CDs for next to nothing" offer pretty soon and I'm going to get either So far... or Peace Sells..., probably the former.
Do get both, there is just too much good stuff to miss. When you hear "Set the World Afire / Into the Lungs of Hell", you are going to cream your thongs. But when you hear "Wake up Dead", you're going to jizz up in your eyes.
Also going for some Sepultura, Maiden, Sabbath, Overkill and Death.
Sepultura - Arise, Beneath the Remains, or Schizophrenia (you really should have BtR by now....tut tut).
Maiden - Powerslave or the s/t debut or Killers (get debut or Killers if you want to avoid operatic vocals and go for more 'hole-in-the-wall' punk leanings, plus you already know "Remember Tomorrow", now you can hear it get done properly)
Sabbath - Master of Reality
Overkill - we had a thread on this recently...
Death - Individual Thought Patterns or Sounds of Perseverance
May the force be with you.