The best substitute available for bourbon is Kentucky-style rye whiskey, or any rye, because it can be used as a substitute at a 1:1 ratio for bourbon in pretty much any application. Rye serves as the best substitute and is the best replacement for bourbon when drank straight up.
If you want a bourbon substitute with no alcohol at all, opt for WhistlePig PiggyBack Devil's Slide with 0.5% ABV and 100% rye whiskey. Although the taste will be affected if you drink bourbon neat or on the rocks, the Devil’s Side is considered much better than many other bourbon substitutes.
As a substitute, blended whiskey can be used in place of bourbon, but the flavor won’t be exactly the same. If you use blended whiskey in place of bourbon in a cocktail, your drink might be drier than you want it.
While bourbon is made from corn, Scotch is barley-based, giving it a very distinctively smoky flavor. Although you can use Scotch as a substitute for bourbon in a cocktail, the drink will be a bit drier, with a noticeably different taste.
Although it’s made from grapes, brandy is a distilled spirit with an alcohol content similar to most types of bourbon, with some sweetness in it. Brandy can work in place of bourbon in certain mixed drinks, but the main difference is that bourbon has more of a distinct flavor to it.