I think it might be best if you state what supplement (ie: protein, weight-gain, aminos, thermogenic, volumnisation agent, hemodilators, etc.) you are interested in as all the companies out there have broad ranges of similar products. Most people don't usually purchase all their supplements from the same company due to price, availability, and expected results.
My protein is from Nature's Best but if I use creatine it is from Ultimate Nutrition. I have also used products from BioTest, EAS, and ProLab.