Something like TWGOK,Sora no Otoshimono,Ai Kora or Nisekoi.Must be of a decent length and bonus if it has a good story.Love triangles also ok.I really liked TWGOK and Heaven's lost property.Nisekoi dragged a little.Preferably shounen and don't suggest reverse harem(i have read Ouran)

I would recommend Rosario to Vampire, Asu no Yoichi!, Jitsu wa Watashi wa, Saijaku Muhai no Shinsou Kiryuu, Trinity Seven and Maga Tsuki.

The first two are completed while the rest are ongoing.
Rosario to Vampire is one of my favorites and I really believe you should check it out.

Then there's Boku wa Tomodachi ga Sukunai and Highschool DxD but these two have stopped being scanlated although they are, in my opinion, very decent.

Hope you find something you like.

Sorry but i have read Trinity Seven,Love Hina and Rosario to vampire also

Hayate no Gotoku! It might be dragged now, but volume 1-26 is really the best

Urami Koi, Koi, Urami Koi. don't have much chapter yet as till new ongoing, though, it's just appear like harem, as many female character around the male lead. But only two who actually love him. The amazing thing is not only the girls, but the male characters also lovable

Try Strawberry 100%. It's one of the first harem manga I read, and I've never seen it's match since. The main character is likable and idealistic, and the idealism is is one reason he dithers so long in choosing a girlfriend from all the girls who like him. He has big aspirations, and he needs someone who does too.

The inability to explain main character dithering is the great weakness of most harem manga. This one solves that, and also provides a collection of female characters who are distinct from each other, memorable and lovable, each in her own way.

http://www.mangaupdates.com/series.html?id=48

if you like yandere girl you could try:
Abnormal-kei Joshi (it's full of crazy/psycho girl and the boy is also kind of crazy 😕 )
Kyoudai hodo Chikaku Tooimono wa Nai (the boy is your usual harem mc but the girls is kind of stalker-ish)
Love Tyrant (i don't know how to explain this one but it's good)
Shinigami-sama to 4-nin no Kanojo (this one is a combinanition of abnormal and love tyrant)

if you like non-human girl(monster girl, god, spirit, etc.):
12 Beast (monster girl harem with rpg-like world)
Aoki Hagane no Arpeggio (harem of ships literrally)
Demi-chan wa Kataritai (kind of harem? or not? i don't know but it have 4 non-human girls)
Demon Spirit Seed Manual (manhua, harem in progress but it will be filled with plant girl)
Gou-dere Bishoujo Nagihara Sora (created by minazuki suu creator of sora no otoshimono)
Jitsu wa Watashi wa (seconded this, it's a funny manga)
Kami Sen (Harem of goddesses)
Kami-sama Drop (same as above + childhood friend + first crush)
Kekkon Yubiwa Monogatari (it's lord of the rings meets harem genre, the boy is in a quest to gather 5 rings from 5 princesses to destroy demon king/lord/whatever evil being big boss)
Maga-Tsuki (seconded this)
Magikano (if you include witch as non-human, you can also watch the anime since it cover most of the manga)
Monster Musume no Iru Nichijou (any monster girls you know and don't know, you can find it here. BEWARE it contains lots of nsfw material)
My Love Tiger (same as above but it's mostly loli/little girls)
Nurarihyon no Mago (youkai, exorcist, and childhood friend with a battle mixed)
Omamori Himari (goddess, spirit, exorcist)
Ore ga Heroine o Tasukesugite Sekai ga Little Mokushiroku! (alien girl not the squid-like thing but the to love ru-kind)
Princess Lucia (angels and demons)
Shina Dark (the girls are human but the guy is demon king)
Shinmai Maou no Keiyakusha (demon, step-sister, succubus, demon queen, hero, etc)
Shishunki na Adam (angels, demons, cyborg/android/modified human with a little hint of yaoi. BEWARE it contains heavy nsfw stuff as in hentai-kind one)
To LOVE-Ru and To LOVE-Ru Darkness (you might already read this but if you haven't then try it)
Tsugumomo (tsugumomo is an object that is old enough that it gained life kind of like a youkai)
UQ Holder! (harem of immortals ie: vampire, modified human, indestructible body, time leaper, etc. also has normal girls. This one is a sequel to Mahou Sensei Negima!)
Yaoguai Mingdan (nine-tails, dragon, taoist, etc)
Youkai Shoujo - Monsuga (any kind of youkai)

i think this much is okay right(since i got bored typing this much 😛 )

Hi there
here are some more reverse harem:
Fruits Basket
NG Life
Hanazakari no Kimitachi e

these 3 are completely scanlated, but I know some ongoing as well. if you are interested let me know!

Vampires are the best!My most favorite is Midnight Secretary but my one and only is Kuran Kaname!

About Hayate its so massive can you give me idea what to expect? it doesn't have pointless filler right

Please don't suggest ongoing manga i will die from wanting closure.

@cecropiamoth
I have heard a lot of things about Ichigo can you tell me any similarities it has to to ones mentioned above

@ryoga08
Wow thanks for this massive list but please no ongoing manga 😔 .
I am interested in Omamori Himari and To Love Ru can you tell me more about them?

@dostdashtanyha
Is Fruit Basket SImilar to Ouran?

@dbz4
i will put a little bit of spoiler about the ending in my reply, in case you don't want to get spoiled don't open/read the spoiler.

Omamori Himari is a story about a boy who have a big magic/mana yet didn't know about it. one day at his 16th birthday, he got attacked by a boy possesed by demon and a mysterious girl save him. Later at night the girl visit him and announced herself as his wife and decided to sleep with him ( fyi the girl is a cat spirit and he is allergic to cat ).
Later in the story more spirit/demon girl will get introduced such as snake spirit, tea kettle spirit 😕 , nine tail, and many more( i don't really remember since it's so long since i last read it 🤢 ), there are also exorcist and omnyouji girl.

in the end of the manga the author make it into a harem ending

To LOVE Ru is a story about a normal boy who suddenly meet with a galaxian first princcess(her father is the emperor who rules over all the galaxy) and the princess fell in love with the boy while he actually love his classmate, the story didn't have much battle and more slice of life/school life where the boy will meet many more alien girl and princess.

at the end the boy confess to the princcess but also said that he still love the classmate

the story continued to To LOVE Ru Darkness with the princess's twin little sister coming to earth.

Mahou Sensei Negima! is also good, it's about a teacher and his classroom of harem(it's a girl school 😀 ) and the second half is filled with battle like sora no otoshimono.

they are both reverse harem, one girl and a few boys!
but fruit basket is kind of more interesting!
it's adapted to anime too! you can watch the anime first if you want.
since it's supernatural I kind of like it more.

Vampires are the best!My most favorite is Midnight Secretary but my one and only is Kuran Kaname!