Dunlop Tortex Standard 1,14

These are the picks I always tend to go back to. They are cheap, has the perfect shape for the attack I need in my playing (thrash/death metal), and a sturdy thickness means you can really dig into your strings (thicker strings also necessary) and get the aggressive "punch" you want, without using too much distortion.
Only minor "issue" I have with them, is that I tend to grind the pointy end down after one of two weeks of playing, making them lose the desired attack. But for the price, this isn't something you can really complain about, and is only an issue when playing music where the picks are really taking a beating.