Here's a little app I've been working on, now on the iOS app store: Riidaa - a simple text and PDF reader. It's extremely bare-bones, but it provides the one feature the Files app doesn't have: It remembers which page you were on.
I'm charging a dollar for this one, since I actually intend to keep it up-to-date with iOS changes and will maybe add a few more convenience features as I need them myself.