I use butter, bacon grease, chicken fat (or turkey, if I have it) beef fat, and lard, now, since we raised and butchered pigs this year, and I have plenty of fat to render. I've rendered some, the rest is in the freezer waiting for me to get around to it. I never use Crisco or any other hydrogenated fats to cook with, never buy margarine, either. I'd prefer raw butter, but until I get my own milk beast, I have to settle for store bought butter.
Chicken fat (with onions or without) is yummy to fry potatoes in, and make biscuits or pie crusts for meat pies, but the rendered fat with onions might not be the best choice for cookies or fruit or other sweet pies! The onions don't quite work, there! Nice in breads, too.