Syrups are perfect to use not only for drinks mixes but also in baking. Some contain stevia and when I add them into the baking it reduces the amount of additional sugar substitutes.
I always try and read the labels so it contains as much natural sweeteners as possible but also tastes good.
I have tried various brands and out of all I love the most Torani Brand, where you have waste choice of flavours to choose from.
In Austria if needed, I buy Mautner Syrups, which are not completely sugar-free, but have 5 flavours without additional sugar and have only 0,9 Carbohydrates. They are freely available in all of the supermarkets like Billa, Spar, Merkur etc