I have used all too and the oil ones tend to be less to use anyway, I have a ginger one that is for cake makers, and I only need two drops in my yogurt to make it taste. I have a couple of the Dukan ones and get a bit confused with the measurements of them, but they are yummy LOL. I also use preema flavourings from website swedishconnections as they are cheaper and soooo much range.
just recently found klassicool flavourings on ebay, there is a post on the main page just under this one about them.