Like hammers for the HD. I have two I like for the big one, 1 I like for the 16/15 but won't use on the bigger one.
Picks are very subjective and very personal to each player, that's for sure. I make wood and bamboo 'strummer' picks, and have picks made from ivory-nut palm, various plastics (credit cards, plastic strapping, etc), corset stays, and large bird primary wing quills.
Being an HD player and the fact that I love wood, I decided to try some different woods and a bone and horn for picks. From left the right is Palmwood, Coconut, BONE, Ebony, HORN, Tamarind and Haldu. Tried them quickly and yes they each sound different some more than others. And they feel great. Just came today.