I used to use Dunlop Jazz 3 picks and was pretty happy with them. The only problem I found was that they would tend to rotate around when I was playing and I would have to keep adjusting my grip. I found some of the DAVA picks in a local guitar store and decided to try them out as they have some grippy material to hold and they were pretty good, so I changed to them.
These rock control variants do not have that grippy rubberised material but instead are plastic with ribs. These ribs allow you to keep control of the pick when playing and helps you subconsciously keep the pick oriented to how you would play.
The ribs provide a couple of roles. First, orientation as said above. Second, control of flexibility. The closer you hold the pick to the tip, the more stiff it becomes. Great for single note passages and good control and articulation. They become a "thick" pick when you hold them this way. When you move your grip further back towards the logo, they become floppy and you can thrash out some rhythm parts with vigour, without worrying about snapping strings or catching a string on your pick.
These are essentially a 1.5mm pick with a .75 pick built in depending on how you hold it.
Now I have got used to these, it's pretty hard to go back to using "normal" ones.
The Delrin is quite soft though, so with a lot of palm muted metal rhythms the tip of it has worn away quite quickly. Your call if you like that or not.
I like 'em and I'll keep using them!
