Turkish delight: cornstarch or gelatine? I've never made Turkish Delight. I've been looking at recipes and I've seen some using cornstarch and others using gelatine. As these two ingredients are completely different binding agents, the question arises which to use?

On the one hand, gelatine is easier for me, on the other hand I think cornstarch is more authentic (not sure about that).

The reason gelatine is easier for me, is that the cornstarch recipes call for cream of tartar and that's a bit difficult to obtain in Spain. I'll try to find it in a drug-store.
If you want to make real Turkish delight, use cornstarch and only cornstarch. Nowhere on the Balkan have I seen a gelatine-thickened Turkish delight. No Turkish person will recognize a gelatine-thickened candy as lokum. I would go as far as to insist that aromatzied sugar syrup+gelatine = gummi bear, while aromatized sugar syrup+cornstarch = Turkish delight, although some people will feel that this is pedantic. 

Beside authenticity, gelatine-containing recipes are prone to weeping, I have seen questions about that around here. 

Bottom line: I would always make it with cornstarch. This doesn't mean that candy made with gelatine can't be tasty; it is just that if you want what you get in a Turkish shop, you can't do it with gelatine.