I know TFA Cotton Candy is ethyl maltol because of this:
http://shop.perfumersapprentice.com/componentlist.aspx?sku_search=346578
TFA Circus Cotton Candy has EM plus other stuff:
http://shop.perfumersapprentice.com/componentlist.aspx?sku_search=344456
Flavor West Cotton Candy doesn't list ingredients but works/taste the same to me as TFA Cotton Candy.
I've never tried Flavor West Blueberry Cotton Candy, but I'll bet it's EM with stuff added.
You can buy pure EM crystals and mix with PG or water or alcohol to make your own sweetener. Then you know for sure what's in it! You can do the same with Sucralose; I get it powdered from ecigexpress and just dissolve in water for my own (coffee and food) sweetener.
TFA Brown Sugar Extra and Marshmallow flavors show they're using Maltol (not ethyl maltol, but maltol, which their website explains aren't the same thing, but they're described as tasting the same). Anyway, none of those use Sucralose, so would be fine for someone with Sucralose allergy. I'd add maple syrup, FA honey (at very tiny fraction of 1%), and FlavourArt Meringue to the list of flavors that could be used as sweeteners.
Linda at TFA has been super helpful to vapers with questions like this. You might send her an email and ask if there are other sweetener alternatives she knows about. Seeing they use Maltol in their sweetest flavorings makes me wonder if you could use that. They DO sell it as a separate chemical.