Never buy a brand of tequila that does not say “100% agave” on the label. These are only partially made from the blue agave plant, do not taste as nice and carry with them particularly vicious hangovers.
Updates
A great, easily available brand of tequila is Don Julio. The Platinum version is the smoothest and the most expensive, but the Reposado is pretty good at about £10 a bottle. The Blanco version is cheaper and has a bit more bite.
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