I've got one that will eat anything, and one that won't eat anything. Well, I finally got miss finicky to eat carrots, but only because she wanted the tops. And it took a couple weeks of feeding her the tops before she stopped spitting out the carrot part.
I don't use treats to train ( mostly because my mini gets over excited about them). When I do give a treat I usually give her baby carrots, or a small piece of apple.