I have a few different varieties/brands I go through (depending on where I'm shopping from week to week) but in general I'm getting either nutty kinds or peanut butter kinds. This is the one that's in there at the moment. (My local wild bird supply store carries it though, I don't need to order it from Amazon.)

Most of the birds I get in my yard seem to love the nut types. Not only the woodpeckers, but also chickadees, titmice, nuthatches and even bluebirds visit my suet!