I would look to the finished project for guidance in choosing the paper.

If you're making a pinata, a parade float, working out a design, or creating any  object that isn't expected to last long, virtually any paper would do.  This kind of thing is perfect for low-quality recycled paper like newspaper.  You've seen what happens to newspaper when it ages:  it deteriorates.

If you're making something that you would want to keep around for several years, I would go to a higher-quality, acid-free paper.

But if you're making a real work of art that you hope will last longer than you, or sell it as a collectors item/art object, you would do best to use the highest quality materials that you can.

We have a thread on selling your work as art, with discussion on how papier mache is often considered to be a low-cost, low-quality craft material.  Some artists who work in what is really PM never use the term in association with their work.  How a work of art is perceived is very important, esp if you're selling it.

Sue