Akatsuki No Yona... I love how complex the characters are and the character development and the plot and the fact that it is a reverse harem but it is not really... but it is...
if you go to Webtoons.com
not masterpieces but you might like
I love Yoo ... its more of a comedy
Winter Woods
my Dear cold blooded prince
sirens lament
Lookism
Well you can watch the anime if you don't mind a few hints shonen ai
X1999 ... the manga is not completed but the anime (not movie) finished it really well
If you feel like you want to watch x1999 then I will recommend that you read Tokyo Babylon before watching it.
I also enjoy Tsubasa Reservoir Chronicles... just pay attention and read it with no distractions... it can get a little confusing...
Anyone can suggest me any great manga that is in the same level as Choukakou? Because Choukakou is such a masterpiece that I'm having trouble finding new manga to my liking.