Light novel versions specifically, though all of them have manga adaptations and one has an anime adaptation. The light novels are far superior in every case. Lightnovelpub is a good website to read I think all of them except #2. I put the language they were originally written in just in case you wanted to know.
1. [Korean]Omniscient Reader's Viewpoint (close to a tie with #2, but fully translated.),
2. [Japanese]Ascendance of a Bookworm (hasn't been fully translated from Japanese, they'll be done putting it in english in about four years. If you know Japanese sentence structure and some common translation errors, you can read it via google translate on syosetu),
3. [English I think]The Beginning After the End, (This is the one which hasn't completed yet.)
4. [Chinese]Library of Heaven's Path. (By far the longest at 2200 chapters, and requires some ability to skip nonessential text. The author screwed up the ending in the epilogue in my opinion, but the journey is worth it. The reason I think the epilogue is garbage is in the spoiler below.)
Spoiler
I hate harems with a burning purple passion. The main character was against the idea as well until his only equal at the end of the story said it was okay.