In my French reading, partly to continue using extensive reading, and also partly research for my writing of comic books in French, I’ve started reading more children’s books. The J’Aime Lire series from Bayard was an excellent place to start. They publish for specific ages: 6, 7, 8, 9, etc. While the difficulty for a foreign language learner varies sometimes, the books for 6-8 year-olds mostly work for me, and seem to match a ~1000 word vocabulary or A2/B1 level.
One thing I found with reading children’s fantasy novels is that they are very vivid, and it is easy to become engrossed in this fantasy world, with a feeling of wonder. I had the same experience when reading the first volume of Harry Potter (and as a child when reading Enid Blyton). My comic book also has this vividness about it – partly because it is a brightly-coloured comic book. I’m not sure if it is the fantasy element, the illustrations or a property of the writing that makes it so. In the case of Harry Potter it can only have been created via the text, as I read it before seeing any movies of it.