I know nothing about vodka (just buy Stolichnaya when we need some for Caviar) but there is a thread with some real purists contributing on my Ferrari site: Some surprises -
None of them like Grey Goose. They claim there is a Costco brand made by the same company that is the same thing for half the price. They don't think good vodka can be made in France.
Held in great derision are modernistic "flavored vodkas" - watermelon, bubble gum, god knows what else...
Stolichnaya is considered an old-fashioned brand, acceptable - but crude and rough. Same for a local "hand-made" Texas brand - Tito, I think.
They profess to like a Polish potato-based kind called Chopin the best - if there is any concensus. I have never seen it.
Frankly, I can't see what great difference there can be between unflavored "grain neutral spirits" provided they are reasonably pure.