Butter is a more natural product (depending on how it is processed or if it is organic), margarine is far from being natural

Butter is higher in saturated fat, margarine has more unsaturated fat.

So if you think organic products are healthier then butter wins, but margarine wins when it comes to the type of fat it contains.

I like the taste of butter and we have mainly lean dairy and meat products so a little bit of saturated fat isnt the end of the world