Personally I love Chongfai Manual, but the op should be aware that the teenage ML meets the reincarnated FL when she's 6 years old and waits for her to grow up. He has no romantic feelings for her as a young child, it's a gradual thing. She thinks of him as a big brother until he kisses her when she's about 14.
Just from your earlier comment, i thought I'd warn you that you probably wouldn't enjoy it. You should have plenty to try reading now without it though
There ain't many decent novels on this side to be honest if you compare them to actual good books but i'd give "Death Sutra" a shot. It's not only well written (it doesn't feel like the chapters are filled with meaningless sh*t like those useless xianxia descriptions or the common xianxia sentences "you court death, im xxxx... bla bla") and not only the MC but every character feels realistic and ain't just used to move the plot along or make the MC look good (looking at the young masters..). When i finished the first book (chapter 247 or so) i was actually really surprised by the brilliance of the climax. Don't want to spoil to much but if you manage to get into the story you will definitly not regret reading until chapter 250.
Hmmm.... here, The Rebirth of the Malicious Empress of Military L... ...really a malicious empress xDDD
I would also second RTW, the harem tag on it is because Spoiler the MC loves one girl and is together with her for a long time but a second girl has been in love with him for most lf the story and eventually he ”accepts” her love but there is no development between them and so far it hasn’t been revealed if his acceptance is a simple I accept you love me but I can’t return it in that way, it remains to be seen. It’s nothing like the normal harem and is instead a lot more mature about it. I would with what I’ve read so far also not classify it as a harem. some minor spoiler nothing major. Might have missed it but Dungeon Defense has a great MC with brains, it is what I would call semi harem though MC has one lover but is sex friend with someone more powerful.
I'm not sure if this will be something you would like but I really love: The Memorandum of Kyoko Okitegami ( The forgetful detective series ) It's a Japanese novel. The translations are really well done and although there's not a lot of chapters translated yet I'm sure you'll enjoy it if you like detective stories. P.S. There's actually a manga and live action series of the novel if you are really interested in it and can't wait for the novel translation to finish. I'm not sure how much of a difference there is in each of the version but from the parts I've read/watched I enjoyed them.
oh this one is good one. too bad its from alphapholis, so the translation lil bit slow. since its paid novel . this one