Best harem i can say is from Mushoku Tensei 3 people each different and unique and fleshed out on their own. Arifureta isnt bad and the main harem isnt to bad but f me does he have numbers lol plus i honestly found the main story so so and enjoy the after stories more which is now longer then main lol main story is 160 chapters total chapters is nearly 400 which means most are after story chapters lol
Spoiler: Adult Places~ Hentai2read MCStories Second Coming of Gluttony, people always complain that it has a harem but that should be a + for you.