I use Readeck for ‘read it later’ type documents or articles, and Karakeep for data preservation. The only downside that I can think of with Readeck is that there is no real ‘one click export’ of the database housing all your articles. However, you can download the entire folder containing the database and all the zip files and transport them to a new server or make it a backup. Other than that, Readeck checks my boxes. It has an iOS app and an extension for Firefox…not sure about chrome as I avoid it like the plague.