Content: generated vs imported
LingQ's content model is "everything that exists." Its catalogue plus your imports puts a near-infinite amount of authentic native material in front of you, from news articles to full novels. The cost is friction: you choose, you import, you tag, you find something at your level.
LibroAI's content model is "everything you ask for." There is no catalogue to browse and nothing to import; you describe what you want and it is written. The cost is authenticity: stories are AI-written, not pulled from real-world publishing. For learners chasing comprehension and habit, that trade is fine. For learners who want to feel the actual texture of a language as natives use it, LingQ has the edge.