Flotsam and Jetsam are one of my favorite bands and I feel they are really underrated, some pretty high quality thrash with great vocals!
http://www.youtube.com/watch?v=2EzvDXEkTCs = Beautiful EPIC song that I would put in the same league as Master of puppets.
And for those wondering, Flots are still going today sounding fresher, heavier and catchier than ever - checkout this!
http://www.youtube.com/watch?v=Q7NzIDnM6lE
Vocals might put people off but hey, its real singing!