The best kind of Vitamin D is the one naturally occurring in your body. A few minutes outdoors without sunscreen, is the natural Vitamin D you really need.
Unfortunately, most people live in geographic locations where they can only make Vitamin D during the summer months.
I consider myself lucky spending all seasons in sunny California. I am usually outside walking and hiking or reading by the pool and at the beach and don’t have to worry about a Vitamin D deficiency.