Mostly the flat, yellow flower ones. I have some really short, super sharp plastic ball pins I use a lot too. When I use pins...I don't usually pin layers together while quilting, more for organization of stacks, pinning them on my curtain (my version of a design wall), or just auditioning applique stuff. I'm a rebel, lol.

I only use the flat flower head pins, they are thin, sharp, and don't buckle up the fabric :D:D:D

I use clover pins and ONLY clover. I find the other brands don't glide through the fabric as easily. I have two different lengths and like them each for different purposes.

i just use the glass head pins ~ probably like flying v goddess

i like using the applique pins,thin and short and sharp.they can be a pain to pick up,if i am not using a pincushion, i toss them in a saucer while sewing..

i tossed all my pins that got dull.

i use glass head pins, and tiny silk pins (really sharp and skinny) and flower pins (when i need a pin that has a flat head instead of round)i have looked at the fork pins but figure i already own thousands of pins, so maybe when i need to buy some new ones i will try them out

I use ½" lace pins. Another use for fork pins is for when you are sewing up a knitted garment, especially bulky/Aran wool. They don't get lost in the wool. Saved my sanity(?) last winter.

I use IBC silk pins #215004 from Clotilde: .50mm, 1 1/4", 500 to a box.
http://www.clotilde.com
They were recommended years ago by Jean Biddick (by far the best most accurate piecer I've ever seen) as the only pins your machine could safely sew over.
Everyone who takes a few from me to try at workshops or retreats usually then buys a box.
You can see Jean's work on her Gallery page http://www.jeanbiddick.com