If you're wanting to drink the purest form of tequila, look for a Blanco, white, or 1800 silver tequila variety.
In comparison to other forms of tequila, there are no artificial additives in Blanco and it features a more natural taste. Plus, the maturation process that takes place between the distillation and bottling stages in Blancos is shorter than it is for any other varieties so your drink will be as clean as possible.