To Butter Or Oil
To butter or oil, that is the question. But it depends upon what question you are asking, so let's dive into this.
Health
Personally I don't care about making healthy dishes; I care about taste. If it happens to be healthy, then fine, but I don't care if that plate in front of you is today's and tomorrow's total calorie intake. Just put it in your face.
However, many do, so if it is important to you, then olive oil wins hands down. It isn't even a contest.
Taste
Again not a contest. Butter wins. And of course it does, because nobody puts olive oil on their popcorn or sandwich. But it does depend upon what you're doing with it.
Would I put butter infused with garlic, lemon, and dill in a salmon? Maybe. Would I do it with olive oil? Definitely.
Smoking point
This is the temperature where fats start screaming "Nooooo!", but it is important.
Olive oil has a lower smoking point than butter, so therefore this is why you won't find a steak cooked in it. Can't baste a steak if you've burnt the fats.
Baking
For almost everything you need butter. End of. Try whipping up olive oil, it just stays liquid (but is a useful thing to do - I may explain that later).
Toast
Depends what you want. Butter is great at this, but if you drizzle olive oil on it, you could always rub a garlic clove on it, as you would a piece of wood and sandpaper.
Wouldn't recommend adding marmalade after though.
Expense
As always, anything you make, you should always buy the best ingredients you can afford. Yes, you can buy the cheapest options and it will work, but if you are able to go with a higher quality then this is something you should do.
In this regard butter wins because there are olive oils out there with prices that would blow your mind.
Duration
Another check for olive oil here. Butter will last a couple of weeks, but olive oil laughs in the face of butter and is fine for upto 12 months, and possibly even 2 years depending upon the quality (keep it in a cupboard, doesn't like - much like Gremlins - bright light).
So which wins here?
No-one.
It is what you use it for - everything has a purpose - so don't put butter on a salad, and don't put olive oil in your brownies.