Oekaki@Heyuri

I still can't believe that this is the only manga in the seinen Big 3 that is complete.

I didn’t know it’s complete. I finished the second season of the anime, been thinking about getting into the manga.

Are the other big 3 as good as Vinland Saga?

Berserk is just as amazing; far more gritty and dark with small but iconic comic-relief moments.
Vagabond grows from being less about action and more about personal growth, similar to Vinland Saga.
Personally, the latter is my favorite of all time.