It doesn't really matter, the idea is that if you need to use it, you want a liquid sugar product that you can easily rub on the cat's gums.
You can even take table sugar and melt with water if you had to.
For my toolkit, I did buy karo (the clear version), but then realized that I had honey in my cabinet. Luckily, I never needed to use it for Maui, so I just used the honey in my tea and returned the karo to the store...
Seriously though, if you are looking to put a kit together and keep it separate, you may either want to by a small bottle of karo or if you have honey or something in your house, put that in a small container (label it) and put that in your kit.
I do recommend that whatever you choose to use, you keep it in the kit, this way if you ever have to use your kit, you don't have to think about what you have and where it is located.
I also printed the instructions and put that in the kit, along with the name, phone and directions to the vet offices (regular and emergency).