I've been shaving with a brush and straight razor for a number of years and echo David's recommendations. As with tools, buying the best knot you can will reward you with better performance and durability. I also suggest considering what kind of shave soap you're likely to use. Those who lather with cake soap generally prefer a somewhat stiffer knot while users of shave cream often opt for a softer one, as do a lot of face latherers.
I've never encountered a significant odor with my brushes but I've never made my own. My current brush is a Rooney Style 1, size 2 in "Super Silvertip."
Brett
Peters Creek, Alaska
Man is a tool-using animal. Nowhere do you find him without tools; without tools he is nothing, with tools he is all. — Thomas Carlyle (1795-1881)