I'm no connoisseur, and not the best at describing tastes and smells in words, but here are my thoughts on vodka.
Ketel One is the best! It has a distinctive taste to it that I love, and no unpleasant burn or aftertaste. Ciroc is probably my second favorite. Maybe it's all in my head, but I could swear it has a mild white wine vibe to it, being distilled from grapes. Grey Goose is also nice. Smooth and clean. Might be a bit overpriced, though. I don't like Belvedere at all. It's not that it's a bad vodka; it's actually quite smooth and pleasant, it's just that I don't like the taste of rye grain in vodka. I've heard people say Chopin potato vodka is amongst the best on the market, but I thought it tasted like potato rubbing alcohol when I tried it. Russian Standard is one of the smoothest vodkas I've tried. It starts off flavorless, then you get a bit of an aftertaste that I could swear is sort of like rye grain, even though it's made from wheat, IIRC. Sobieski is one of the worst I've tried, with a bitter aftertaste. Stolichnaya seems to have a bit of a burn to it.
Oddly enough, I prefer Smirnoff's vanilla vodka to Absolut's. Smirnoff is more like vanilla beans, Absolut is more like sugary syrup. As a side note, vanilla is the only flavored vodka I will drink straight.
Edit: If you want a good martini- 2 ounces of vanilla vodka, 1 ounce of absinthe, and 3/4 of an ounce dry vermouth. Best thing ever.
