I think it should be a states rights issue. But I also think that a couple states should go full legalization and the others should sit back and watch the results for ten years or so.
Having been to Washington State recently and seen hordes of shiftless stoned out young people waiting in line for free food, I have a pretty good idea where the results will come in, should they be honestly reported.
On the medical side, if one has a truly chronic or terminal disease, do whatever you want. My state recently passed medical marijuana laws and judging by the number of dispensaries that have opened, our state must lead the nation in chronic illnesses, or people and doctors are just cheating.
Cultivation and possession for personal use has been legal in Alaska since 1975 (43 years). Retail sales was legalized in 2015.
Constitutional carry, more guns than people in my town, legal pot for more than forty years. Virtually no crime.