I couldn't find a dedicated recommendation list for this, so I put one together.
P.S. I also have recommendations for fanfiction in some less popular categories from other anime and novels. Feel free to take a look.
One Piece (OP) fanfiction recommendations http://www.jjwxc.net/onebook.php?novelid=531048
Harry Potter (HP) fanfiction recommendations http://www.jjwxc.net/onebook.php?novelid=567067
Detective Conan fanfiction recommendations http://www.jjwxc.net/onebook.php?novelid=567450
La Corda d'Oro fanfiction recommendations http://www.jjwxc.net/onebook.php?novelid=590897
Case 7 / Kaifeng Prefecture fanfiction recommendations http://www.jjwxc.net/onebook.php?novelid=591276
Gakuen Alice fanfiction recommendations http://www.jjwxc.net/onebook.php?novelid=590901
Shugo Chara! fanfiction recommendations http://www.jjwxc.net/onebook.php?novelid=591285
Highly recommended: (Caiyunguo Monogatari fan) Tea Sitting This is a BL article The male protagonist is Cha Shuoxun~
Self-recommend~ □//www. Jjwxc. Net/onebook. Php? Novelid=484225 My name is Zi Ruochen---a fan of Caiyun Kingdom Monogatari
I've read this article, it's great! Recommend!