Fat is what matters in your food. That's the key thing to remember about fat. The lean mean tastes like whatever; you couldn't tell a thin slice of chicken breast from a carpaccio if your life depended on it. No, “The fat is the meat, and the meat is the vegetable,” as the saying goes, and this is especially true of real fat, the kind that comes from animals.
I should clarify here—so to speak—that I am not talking about the revolting white fat that sits congealing on the plate when they slice open the prime rib. No, I mean hot fat, crispy fat and most of all liquid fat, the kind you can roast or sauté things in. Most herbs and spices, as volatile organic compounds, are fat-soluble, so it's not hard to give the fat you use deep flavor—deeper than you ever get by just seasoning the food. I use Aleppo pepper, rosemary, chiles, sage and whatever else I can think of to put into it.
But are all fats created equal? I don't think they are. I think there is an eternal hierarchy of Seven Great Greases, as I have come to think of them. They are as follows.