I prefer margarine, too many calories in butter.
To cook, whatever I have at hand. I don't tend to put butter or margarine on my bread.
I hardly ever have butter on hand. I don't eat much bread, sometimes toast for breakfast and then I usually put Jelly or sugar/cinnamon.
I use real butter for cooking. As a spread, I use real butter softened with olive oil.
I hardly ever buy real butter, but I do serve it when having company. lol
both are fine by me , I usually buy reall butter and one box lasts more than a year in the freezer until i need it.
wow, I didn't know it could be frozen.
For cooking (for example, for keeping pasta from sticking), I usually like margarine better.
As for putting it in bread: if I'm going to toast it / heat it in the oven, then I like both without much difference. But, if I'm not going to toast the bread, then I usually prefer butter.
Butter, only butter, and I often make my own cultured butter.