definitely Pantera, but metallica is a close second. pre-st. anger metallica, that is. i don't really like slayer that much, and i don't like megadeth very much either.
Errr...so hard to choose... Its a tie for me between Metallica & Megadeath. Although I haven't heard much Pantera, I still think they're cool. Slayer...Dont really like 'em & I havent heard much of thier stuff.
Megadeth, Slayer, Metallica then Pantera. I can put on a Megadeth album and listen to it the whole way through. I do the same with Slayer, but Megadeth is always a good choice, sometimes Slayer isnt. Metallica's best songs dominate anything by all of these bands, but I RARELY listen to an entire album in one sitting. As far as Pantera goes, not a big fan. Some songs are great but meh...