One piece & no other can come close.
expected from fan of chokers
only one i read was Tower of God B)
You don't like berserk after the golden age??
manga is great!
Is Korean I think but is really good. Legend of northern blade
holyland and kingdom are solid choices honestly, but the best one would be the Baki Hanma series.
ouch, tough question...
I have a lot of favorites depending on the style... Silver Spoon, Rurouni Kenshin, King's game (the first one only), Underwater, Minuscule, Doubt/Judge, ...
Berserk is huge but as we won't have the end before years, I can't make a statement on an unfinished story.
You forgot prison school, if we complitely ignore the ending.