Hey RLP4ever, we got ourselves another Thrash/Speed Metal fan here.
With that out of the way, I like to say welcome to the bands, and man, that's an impressive list you got there. I myself like the "big 4" (Anthrax, Megadeth, Metallica, and Slayer), but have heard some stuff here and there from your list, like Voivod's cover of Pink Floyd's Astronomy Domine. I'm very happy that out of the big four, Megadeth is your favorite with your liking of the whole catalog, which over the years, have very different eras (Roots, commercial, back to their roots). I'm guessing you're bit disapointed with Metallica's Death Magnetic? Well for me, it's not that essential, but I can see why. Again, welcome to the boards.