No slushies for me, please, and I try to avoid working in bars that have blenders....
What I like to make is an old school margarita, so no pre made sour mix, and no tall glass. So in a rocks glass, or tumbler, I'd do a shot of good tequila, a reposado or anejo, Cointreau, not triple sec, fresh squeezed lime juice and a drop of orange juice.
But I do enjoy all those ingredients with store bought sour mix too. Whats important to me is decent tequila and Cointreau over triple sec.