LoveVanilla's right about that FW Butterscotch-diacetyl. I used to use it for the flavor of those yellow disc candies in the cellophane wrapper. It's definitely the flavor of candy.
FA's Butterscotch is like b'scotch syrup in flavor and sweetness. It's just too strong and sweet for me as a standalone flavor
I like 2% FA Butterscotch with 1% FA Brandy for Buttershots (butterscotch schnapps) flavor with the sweetness dialed back a little.
2% FA Butterscotch with 1-1.5% FA Fresh Cream, for creamier, less sweet flavor
2% FA Butterscotch, 1% Fresh Cream, 1% Vienna Cream for sweet, rich, smooth, b'scotch with a little hint of vanilla
1.5% FA Butterscotch, 1% Fresh Cream, 1% Vanilla Tahiti for smooth, mild, vanilla-butterscotch (or V.Bourbon for darker vanilla, a little less sweet)
FA Butterscotch with FA Caramel is like combining the ice cream toppings. I prefer a combination to either one alone. Any of the above could use a combo instead of plain b'scotch. It creates a slightly 'darker' flavor, adds some good complexity, and it's a little less sweet.
A little bit (1% or less) of Brandy or Rum in any of the above just makes it taste better. Think 'butter-rum'....yum!