IMHO, the "best" choice in vodka depends upon what you prefer to drink. If you are a vodka martini guy or drinking it straight, it makes sense to go with a higher-end brand you like. NB, your definition of a high-end brand may differ, as some may consider, say, Absolut or Grey Goose as being so while others may not. However, if you mainly want to drink mixed cocktails, such as a Bloody Mary or Screwdriver, there is no good reason to pay a premium for your vodka. Smirnoff has won a number of blind taste tests, and will work perfectly well for you.
In short, if you stay away from the Popovs of the world you can't go wrong.
