I had a surprisingly difficult time finding stories for this pairing that felt true to her character for a long while. A lot of platforms bury the good stuff under mountains of content that's either poorly written or veers wildly into territories that don't feel like Hermione at all. My absolute strongest recommendation is Archive of Our Own. The tagging and filtering system is a lifesaver. You can search for Hermione Granger/Reader, then filter by kudos, bookmarks, or comments to surface the top-rated ones. I often sort by word count too, because a longer fic usually indicates more developed plot and character. Don't ignore the collections either—users often curate 'Best of' lists for specific pairings. Another spot, though it's a bit of a deep dive, is specific Hermione-centric communities on LiveJournal that have archives, though they're less active now. The key there is finding a community that had strict moderation for quality. Honestly, skipping the generic search and going straight to a dedicated rec list from a trusted blog on Tumblr saved me hours of sifting. There's this one blogger who only reccs fics with Hermione in-character, and that's been my gold standard.
I'd advise caution with some of the bigger, more generic fanfiction sites. The signal-to-noise ratio can be frustrating. Sometimes the highest-rated story on a given platform is the most popular, not necessarily the most nuanced portrayal of her. I look for tags like 'Canon-Typical Hermione', 'Intelligent Hermione', or 'Hermione-Centric' as a good sign. Comments sections are also a treasure trove; if readers are discussing her motivations and choices in depth, that's usually a green flag. I remember finding this one story where the reader was a Muggle-born in another house, and their dynamic was all about academic rivalry turning into mutual respect, and it just got her voice—that stubborn, principled, fiercely loyal core. It’s out there, it just requires a bit of patience and knowing how to look.