I have only recently started to listen to the Metal genre; I started with Metallica and Megadeth etc.... But then I stumbled upon Slayer, I got a couple of albums and I just fucking loved them. I listen to them frequently and can't get enough; Slayer have been a breath of fresh air for me, I think the lyrics and music composition is excellent and the sound is just so raw: It's awesome.
The best think about Slayer is their versatility, which can be seen in albums such as Seasons In the Abyss; and from what I've heard World Painted Blood.