well, the refractometer with SG scale is only accurate to about 1.040. After that, you have to use a calculator to predict the sugar levels. This being said, I would get the one with the SG because they are about the same price. I got mine at morebeer.com but they are all about the same as far as quality goes, IMHO. Right now morebeer is saying they did request better scales just for brewing.. but I don't see them advertized.
Northern Brewer also has them with ATC for $59. I probably broke over $59 worth of
glass hydrometers, but you can break these things too if you are clumsy. Still, I love just placing a drop of wort... awesome.