Fine granule salt is my first choice for seasoning freshly popped corn. These Morton shakers are just the right size to maintain freshness and mitigate caking of the salt by reducing its exposure to moisture in the air.
I often search for this brand at local grocery stores and discover that it is not carried! As a result, I order this pack through Amazon and keep a generous supply in the pantry. To Morton's credit, this 3-pack is a competitively priced relative to other brands.
Other salt products may be mixtures containing additional ingredients and the lopsided proportions of each don't always improve the flavor of a popcorn experience. When desired, I can add independently a buttery shaker or other flavors as desired.