The most overrated would be any Pappy bourbon. There are probably 30 or more bourbons (not counting Tennessee, Canadian, Irish, Scotch, Japanese or ryes) I would go with before grabbing a Pappy and that's without factoring in the ridiculous cost.
The most underrated for me is probably a tie between the Kickin' Chicken aka Wild Turkey 101 and Monkey Shoulder. Wild Turkey 101 is always considered and priced at bottom or second from the bottom shelf, but I and a ton of whiskey reviewers usually have it as one of the best. It's not my all time favorite but is way, WAY up there. Its got nice spice to go with vanilla and the oak starts to creep into the palate when you add some spring water or ice. Monkey Shoulder on the other hand is a premium Scotch at mid shelf price. Unlike a lot of blended whiskeys like the vastly overrated Johnnie Walker Blue it has no grain alcohol, just three single grain malts. It's a mix of three Speyside Scotchs: Glenfiddich, Balvenie, and Kininvie that are blended together and aged an extra 3-5 years over their original 5 years separately. And all for under $30 usually.
The most underrated for me is probably a tie between the Kickin' Chicken aka Wild Turkey 101 and Monkey Shoulder. Wild Turkey 101 is always considered and priced at bottom or second from the bottom shelf, but I and a ton of whiskey reviewers usually have it as one of the best. It's not my all time favorite but is way, WAY up there. Its got nice spice to go with vanilla and the oak starts to creep into the palate when you add some spring water or ice. Monkey Shoulder on the other hand is a premium Scotch at mid shelf price. Unlike a lot of blended whiskeys like the vastly overrated Johnnie Walker Blue it has no grain alcohol, just three single grain malts. It's a mix of three Speyside Scotchs: Glenfiddich, Balvenie, and Kininvie that are blended together and aged an extra 3-5 years over their original 5 years separately. And all for under $30 usually.