Brands of creatine

Does anyone know anything about the quality of Met-Rx Creatine AC, Chemical Nutrition’s creatine or Champion Nutrition’s creatine?

I´ve tried both Creatine AC as the creatine from Chemical Nutrition. Both are very good brands. After taking regulary creatine a few times I stopped responding to creatine. Then I tried Creatine AC, I gained 5 pounds in ten days.