I learned from a friend that for great tasting popcorn without the butter you should use coconut oil.  I found coconut oil at my local grocery in the organic section.  It threw me off a little because it is a solid, but
it turns to liquid at a very low temperature. 

I use 3 tablespoons of coconut oil and 1/3 cup of popcorn.  Salt to taste.  You won’t be disappointed!