Please vote in my new poll over there in my sidebar: how important is it to you that the paper in your planner and/ or notebook is acid-free?
Acid-free paper is less likely to break down over time and fade your inks, so it is an indicator of archival quality paper. Many brands specifically say they use acid-free paper (click here see my post on which brands I know of that use acid-free paper).
Personally, I specifically look for planners and notebooks that use acid-free paper. I keep my planners and notebooks forever, and I want to be able to read them decades from now.
In fact, acid-free paper is so important to me that I'll buy a product I otherwise don't prefer (for example, Moleskine with its too-dark paper and boring black covers) because I know the paper is acid-free.
What about you? Will you only buy a product if you know the paper is acid-free? Is it an added bonus for you if the paper is acid-free, but if it's not you'd buy the product anyway? Or is acid-free paper not at all important in your purchasing decision? Please vote!