3mm Dunlop pick is mainly used by jazz players, but is also applicable to shred. It's well rounded, and requires less energy for picking. I try to have one at all times, because it affects my style - I tend to sound more fluid with it than with a regular flat pick.
Heavy picks don't bend => you know the exact position of the (pick) tip at every moment.
You can also use smaller part of the tip to pick.