no one knows the most potent strain, unless a strain was stablized for potency which is incredibly difficult to do, the potency will change in every plant of that given strain. Not to mention will change with growing conditions. The strain with the highest THC content to my knowledge is HP13, which is the Hash Plant inbreed thirteen times. Its like a whole different high. That and Mothership but I don't know of any place online where you can purchase these strains...