I only buy unsalted butter and I use that in baking unless the recipe specifically requires something else. I never use margarine for anything and I think my MIL and SIL find this a bit snobbish.
For you to be here now, trillions of drifting atoms had somehow to assemble in an intricate and intriguingly obliging manner to create you. It's an arrangement so specialized and particular that it has never been tried before and will only exist this once.
--Bill Bryson, "A Short History of Nearly Everything"