Thats a good question and has two answers.

In less then an hour drive east or north, we can be deep into the mountains that have never seen a human and has no shortage of water....so in this case, it would be fire.

Yet drive an hour north and slightly west, which is our fav area for outdoor activities in the summer. It will be water as this area is almost desert like and has the hottest summer temps in Canada.

Back to the egg carton tinder. I don't use these a lot, however they have never failed me yet even after getting wet from a dunk in the river.