Most of the time I use .71mm Dunlop Gator-grips (I think that's what they're called) on all guitars. Once in a while I'll use a heavier or lighter one, but only for unusual circumstances. For my pick attack and style the Gators sound good. I have flirted with the Dunlop Nylons with a similar feel to the Gators because they're so easy to hold, but the attack sounds a little more plastic to my ears. I'm more likely to use the nylons on electric guitar.

On mandolin I use one of the two blunt corners of the .96mm Gator.

For fingerstyle I use a Fred Kelly thumbpick and nails.

For special effect I will use a Dunlop Strumrose, or picks made from aluminum, coins, wood or bone. Being basically lazy however, I don't often stray from the .71s or .96s.

Many of my guitar students like picks with weird designs on them, unfortunately learning that these cheaper ones don't last too long but they feel cool in the meantime.

Like others, I will reshape a pick or restore the edge/point with fine abrasives, but before they wear too much I let students take them.

Peace, Mooh.