My Big 7 of Thrash (US) would be Slayer, Metallica, Anthrax, Megadeth, Exodus, Overkill, Testament.
My Big 7 of Thrash (EU) would be Kreator, Destruction, Sodom, Tankard, Onslaught, Holy Moses, Exumer.
7 of the Best of the rest would be Sepultura, Razor, Voivod, Infernal Majesty, Hobb's Angel of...