Both Torani and Monin products are made with sucrose (cane or beet source) and are all natural flavors. Note that "natural" doesn't necessarily mean the Cherry syrup contains flavors from cherries, it means the Cherry syrup contains things from a natural source that is evocative of cherries. That might, or might not, include cherry juice. Monin products seems more likely than the Torani to contain the cherry juice.
Monin has some artificial colors, but no preservatives (which it could do with). The Monin bottle is much nicer than the Torani because it has a "glub-glub" type restrictor than makes for neater pouring. This couples with a plastic inner cap that provides a much more air-tight seal than the simple Torani lid. Again, because of the shorter shelf life and lack of preservatives, keeping air out is probably a good thing. In general, I think the Monin products are better that the equivalent Torani's, but note the Monin's are also usually more expensive than Torani by a buck or two, nor do they last as long on the shelf.
I really wish Monin would come out with a line of "reduced carbo" syrups which has the bulk sweetener replaced with sucralose. There isn't any reason to destroy the integrity of the flavor to make 0-calorie product, just reduce the calorie count to a reasonable level! Now that would be a great line of syrups!
Torani is an "extract" style syrup, while Monin is more like a "concentrate" or "juice". Unfortunately Monin flavors don't seem to be as stable as Torani in storage. The average Torani syrup is probably still OK after 2 years, the average Monin about 6 months.
I've also listed one Essena d'Italia, which is supermarket-style brand. They contain artifical flavors, maybe that's why the Vanilla is so good.
Da Vinci has both artificial colors, flavors and preservatives, but is remarkable in that they make a line of Splena (sucralose) sweetened sugar-free syrups. Note that some distributors/stores may still have inventory of the Nutrasweet version of the same flavor. Da Vinci also doesn't use enough glue to stick the liner inside the cap, it invariable ends up stuck to the bottle instead of the inside of the cap.
My first method was simply to taste a teaspoon of the syrup in question. This method turned out to be giving some false negatives. Mango, for example, is repulsive straight from the bottle.
I still taste them "straight", but my prefered test is to dilute them 3 to 1 with soda water. This approximates the actual concentration of the finished product, but gives a better sampling of the aroma and flavors. Mango at this dilution is quite tolerable
Sometimes the formula changes (or perhaps the quality control improves), these results are from the last sample I tested. Some flavors can move up or down the scale, most recently both Torani Kiwi and Lime moved up from "ick" to "ok", while Torani Lemon recently moved up from "ok" to "good". Progress, I guess.
Sucralose sweetened syrups are difficult to test straight, as the sucralose "stuns" your taste buds at that concentration!
Monin makes a line of 5 sweetened tea concentrates.
Be sure to visit the real (corporate) Torani, Monin and Da Vinci web sites for ideas and recipes. If you are a manufacturer and want me to test (or re-test) a product, drop me a line.