Marijuana stocks have been an area of tremendous investor excitement -- and tremendous risk. In fact, some people have argued So the big question, then, is this: are there any marijuana stocks worth buying? We asked some of our top analysts for their take.

Brian Orelli: If the question is whether to buy companies selling marijuana itself, the answer is still a resounding no. There's too much uncertainty with the Federal government prohibiting its sale. And most of the companies' shares aren't listed on the major exchanges, which has its own set of potential problems.

Now if we're talking about a company like GW Pharmaceuticals (NASDAQ:GWPH) that's seeking to turn marijuana into an FDA approved substance, the answer depends on your time horizon. After gaining 500% over the last year, GW Pharmaceuticals has a market cap around $1.8 billion, which isn't cheap considering it's still a few years away from having a drug on the market with any appreciable sales. (Sativex is being sold in 11 countries, but GW Pharmaceuticals only sold $2 million of the drug in its most recent quarter.) If you're investing for the short term, I'd be cautious about buying at this point.

If you want to hold for a few years -- and willing to deal with the volatile stock price that could drop 25% for no apparent reason -- GW Pharmaceuticals could be a good pick. Early data on Epidiolex for childhood epilepsy look promising, and there's a true unmet need, which should give GW Pharmaceuticals pricing power, helpful given the small market.

George Budwell: And I want to emphasize a little more heavily the issue of valuation. GW Pharmaceuticals has perhaps the best chance of actual success over the long term of the marijuana stocks. As such, investors have flooded into this stock in the search for "green-gold", leaving it dangerously overvalued. I mean, the company only has roughly $48 million in annual sales and its marijuana-based treatments may never live up to their promise. 

Sean Williams: The medical marijuana market was worth $1.7 billion as of 2011 and, according to a Medical Marijuana Markets report released that same year, was expected to balloon into a $9 billion market by 2016. The treatment options are a-plenty, and close to half of all U.S. states are onboard with legalization of marijuana for medical purposes; but that doesn't in any way make marijuana a safe investment.

We have one, exactly ONE, approved marijuana-based pharmacology product to derive our opinions off of, and that's GW Pharmaceuticals' Sativex. Despite being approved in more than a dozen countries (but not in the U.S.) sales of Sativex have been disappointing. I suspect medical marijuana and cannabinoid-based compounds are going to run into a multiplicity of issues in the U.S. including marijuana's current scheduling as a high-risk drug by the Drug Enforcement Agency, as well as physicians' possible unwillingness to prescribe marijuana-based pharmacologic products.

As an investor we also have to consider the rampant speculation that's already been priced into marijuana stocks. GW Pharmaceuticals, for instance, is valued at roughly 15 times Wall Street's projected 2017 sales figures. Furthermore, the company is forecast to burn through more than $180 million in cash between now and the end of 2017.

Marijuana stocks may have offered potential once upon a time, but that train has gone up in smoke and left the station. 

Todd Campbell: Harsh, Sean! Me, I'm actually interested in Insys (NASDAQ:INSY), which has a unique advantage over other medical marijuana companies: it makes money. The company's Subsys competes against fentanyl opioids used to treat breakthrough cancer pain and despite winning FDA approval just two years ago, Subsys has become the fentanyl market share leader. As a result, Insys sales totaled $55 million in the second quarter, up from $18.8 million a year ago, and leading to a quarterly profit of $9.5 million. 

Insys has another advantage, too: it already has a medical marijuana drug awaiting FDA approval. In August, Insys filed for approval of dronabinol, a new formulation of Marinol, a synthetic THC medicine widely used to battle weight loss in HIV patients and vomiting and nausea in cancer patients.

Dronabinol works faster, remains at more consistent levels in the body, and allows for easier dose adjustments than Marinol capsules, so it could have nine-figure potential given that the market is worth about $150 million. In addition to dronabinol, Insys also working on CBD treatments for epilepsy and brain cancer. And there's also one more reason to buy: while investors in competitors fret over valuation, Insys trades at just 18 times expected 2015 EPS.

Todd CampbellSean WilliamsGeorge Budwell, and Brian Orelli have no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.