Haha, simply impossible to tell. I love songs such as Four Horsemen, Fight Fire with Fire, Fade to Black, Master of Puppets, Orion, Blackened, One, To Live is to Die, Bleeding Me, Outlaw Torn equally. Yeah I skipped black album, Reload and St Anger cos they're shit. I like Load though (and Frantic + Some Kind of Monster of St Anger are okay).
I'd say The Unforgiven, The Unforgiven II, One, Sanitarium and Fade to Black are all amazing. In terms of the thrashier side, I'd go for Blackened. There's many great tracks though, whether you love them or hate them.
for whom the beels toll,fade to black,trapped under ice,one, dyers eve, unforgiven, unforgiven 2, carpe diem, bleeding me, outlaw torn, sanitarium, orion,and lots of other great song. haven't bought the new album yet and i don't know if i will.