best intro dark liquor?

hi, i’m trying to expand my tastes as best as i can and want to be able to have a good scotch/whiskey/bourbon/dark liquor of some sort that i can pour a finger or two of and drink straight. however, i’m not good with particularly bitter and sour flavors (or smokey) and am very prone to consuming fruity, sweet alcoholic drinks. i know this will be a large learning curve for me, but i want to develop the taste for it!

do you have any recommendations for someone who doesn’t have a particularly refined palette? thanks!