for starters i would say round edges are a must for cf hoods. personally, i like being able to use my washer nozzles so that might be a factor to consider too since some prefer the clean look and choose a hood without predrilled nozzle holes. even if you do choose one without, there are usually indentations for you to drill in your own.
interms of brands...everyone on these boards will tell you very mixed reviews about each company. some of the more popular ones are VIS (which i have and am very happy with), and fiber images.
oh yea..shibbism is right!! clearcoated and uv protected are a MUST as well!!! i went through 2 shitty ass hoods that werent uv protected before getting my VIS. fading occurs when not properly coated with some sort of protectant.