[Overnotee]

I've stuck to some of the more popular series like AOT, Solo leveling and BNHA.  
Are there any under rated or sleeper good manga series out there?  I'm open to any genre.

[Haashi]

I've got some like:

Omniscient reader viewpoint
Her summoner
Zense coupling
Horimiya
Terror man
Mushoku Tensei
The beginning after the end

[clownfish6969]

ONEPIECE nothing else

[Gottaeatramen]

Mushishi
Re life
Onnai master kurosama (worth reading)

[TerryC]

Berserk. The thing is it's probably never going to be a concluded series.

[Robert Silva]

Hunter x Hunter. Berserk is a good one.

[nndynn25]

Homunculus is a messed up but interesting one