OK... I'll give it a shot.....
Without getting into double wall vs triple wall, aluminum liner vs SS liner, positive pressure flues and a few other variables, when I did flue work the only thing I looked for when deciding which brand to buy for a job, all things being equal, was price and the length/selection of their pieces. Basically they are all the same, just with a different way to connect the joints and one brand may offer a broader selection of straight pipe lengths, adjustable joints or may have a broader fitting selection, such as a 30 and 60 degree elbow along with the standard 45 and 90. Most prefabbed flues even come with their own roof flashings, which may or may not suit your particular roof (for example, your roof may hold a lot of snow, but the flue only comes with a short cone flashing). If any of that affects you.
Also, a nearby supply house that stocks a particular brand may be a good choice in case your tape measure wasn't working properly that day /forums/images/graemlins/blush.gif. You normally can't mix and match.
Just trying to give you some things to think about to help you decide.