The better brands will use better components. They will usually be aluminized and use mandrel bending. It looks much better, and the madrel bends help performance. If it is a daily driven beater go cheap. If it is something you want to keep and you are spending alot on the rest of the car, dont cheap out on the exhaust.
I would buy the mufflers and have an exhaust shop fab up aluminized pipes. I had mine done in 3 inch duals for $150 installed, but I supplied the mufflers and turndowns.