Any, amazon have several 6GB ram/64GB storage for $50-60 many of them even have a microSD slot for more storage, they'll all do fine for reading PDFs, my first

Any, amazon have several 6GB ram/64GB storage for $50-60 many of them even have a microSD slot for more storage, they'll all do fine for reading PDFs, my first iPad had 32GB storage and it did that task just fine. Heck they have 4GB/32GB tablets for $30 that would no doubt just about manage running ReadEra or some other PDF viewer with no trouble.