Almost any clean paper will do well, especially when crumpled (do not be confused with plastic "paper"). Dangers of a modern printing ink chemistry are overrated, imo, especially in a survival scenario. So I'm stashing real paper (e.g. mail ads and old phone books) invisibly under the furniture. It's filling the volume otherwise occupied by dust, have more uses than typical TP, e.g. burns much better, mechanically stronger, have some information printed on it to occupy your mind, and is virtually free.
By the way, plastic "paper" is not that bad either, e.g. as a single use plate/platter, cutting board, and wrapping material. So' I'm stashing it too but separately from the real one.