I think the "green" versions of denatured alcohol are the safest and most practical form of alcohol stove fuel. Everclear would top my list, but it isn't available in all states and it is much more expensive.
The non-green denatured alcohols sold in the US have up to 45% methanol AND a witches brew of other "adulterants." Methanol is poisonous and I don't relish getting it on my skin or breathing the fumes, but not knowing the actual ingredients and their proportions are a broblem for me. Read the MSDS sheets on the stuff: you have no idea what is in the mix you have at any one time.
The track record for dealing with health issues with industrial chemicals isn't very good. We used benzene for solvent in the printing industry and I spent many hours in photographic darkrooms bathing in stuff like selenium toner. Other chemicals like carbon tetrachloride and PCB's were in common use until the health risks and environmental impacts were obvious. We used to handle mercury in science class, BPA is still in use, etc.
The thing to remember when you get in bed with the petrochemical industries is that their hearts are kept in the same freezer with the rest of the Wall Street players. IMHO, denatured alcohol is a dumping ground for leftover byproducts from refining.
The fact that denatured alcohol is labeled for use with marine stoves is meaningless to me. My personal judgement needs to be to be the first layer of defense when it comes to my health.
At least with the green types of denatured alcohol offered, the total proportion of adulterants is much smaller— more like 5% rather than 45%. I would think that a more consistent product would help with stove design and estimates for fuel use.
Isopropyl hasn't impressed me as being an alternative, but I would like to see the stoves that have been successful using it.
For those of you working on stoves that use isopropyl, purer forms (98.9%) are available through electronic supply houses. http://www.techspray.com/p-8-isopropyl-alcohol-ipa-998.aspx. It runs about $30 per gallon and shipping would be significant, so finding a local supplier would make it more practical. For comparison, 190 proof Everclear is $41 for a 1.75 liter bottle in my state.