It depends entirely on the device you're using. Higher quality grinders tend to use stronger steel metal which holds a "blade" longer so it actually cuts the herb as opposed to simply smushing/tearing the herb.

Over time the cheap grinders wear out, and the really cheap ones start flaking metal or paint into the ground up herb which you really don't want to smoke.

Additionally there are different types of grind. A fine grind is great for conduction style vaporizers (like the Pax) where the oven heats up and the heat is physically transferred through the load of herb. Fine grinds help for cloud chasing and a more thorough extraction.

For other vaporizers like convection style desktops, a loose fluffy grind like the Santa Cruz Shredder or the Brilliant Cut grinder (with a coarse or medium grind plate) help produce fluffier grinds that help enhance the vapor flavor during conduction extraction.