I don’t use any sour mix at all in my preferred tequila cocktail - just two parts good tequila, 1/2 part Cointreau, and 1/2 part sweetened lime juice (equal parts fresh squeezed lime juice and agave nectar). Shaken cold and served straight up in a martini glass with a wedge of lime. Even in that drink you barely taste any alcohol, but I always use a good reposado tequila.
For Margaritas mixed in a pitcher and served with tacos or fajitas, etc., it’s 3 parts sweet sour mix, 1 1/2 parts tequila (not necessarily reposado, but always good agave tequila), 1/2 part triple sec and 1/2 part Rose’s lime juice. You really don’t taste alcohol in that drink, either. Decent tequila generally isn’t more than 80 proof, so you’re not going to get the alcohol taste you do with 90 or 100 proof liquors.