i use generic fender mediums, when i have them, but i have used pennies and dimes before, a quarter would be a bit too large for me to play with comfortably.......
THE most famous coin user the DOES for real use coins is Brian May, he uses a six-pence
I think my favorite right now would have to be planet waves black ice picks. the xtra heavy variety. I have played with jazz III xl's for a long time but i like the feel of the black ice much better. Any other suggestions, styles that are similar that i should maybe try?