Librera is great. A few pros:

• half page display (to read one column at the time, a common layout in RPG rulebooks for example)
• bookmarks
• dark mode (pictures look funny but makes black-text-on-white into white-text-on-black)
• tags and library management
• autoscroll (I didn't think I would like it until I tried)
• for ebooks you can set your own color schemes (if you prefer yellow text on gray background for example)