These are my go to picks for fast riffing of any sort. If i have to play something complex and fast, these are the best! If you look at many other heavy metal guitar players you'll notice majority of them play with fairly heavy picks like the 1.14mm ones or so. It's thick enough to there isn't any of the flappyness and yet thin enough where the tone doesn't add TOO much. These picks give a rather thick tone and to some, can muddy up your guitar tone depending on how you use it, if that's what you want going with this thickness or higher is a good start.

It's also heavy enough so you don't have to dig in so much and still get the same amount of attack with less effort in your wrist, so you won't get fatigued too early. Again the tortex picks wear out quite easily so you either gotta buy a lot of'em or look into the ultex versions, they seem to be lasting a lot longer than the standard tortex ones.