I use a lot of kibbles, but the kibbles I like to use, I don't feed my dogs (Solid Gold kibbles are my favorite for training with, yes large). I feed Fromm Salmon when they eat kibbles, and those are TINY (but perfect for the Treat and Train).
I use a lot of Natural Balance food roll. Lamb is extra gooey and stinky.
I have biscuits on occasion and sometimes they're fun for jackpots, my dogs like to crunch things... bison biscuits have been a HUGE hit here, whenever I feel like buying them.