Good weed is good weed, regardless of where you buy it. You're more likely to get better pot from a dispensary simply because there's more quality control. They're out for quality, not quantity. Though, medical pot in Canada is pretty shitty unless you know a grower. The government pot is essentially tossed in to a wood chipper, seeds, stems and all, and you get a bag of shake that does little more than give you a headache. There's also the different cannabinoids to take in to consideration; you can have some potent shit that only contains 2% THC, but high concentrations of CBD and CBN.