Mine is Berserk, it's really awesome and immersive. Also, it motivates me to work-out and live my life to the fullest. If you write your favorite manga, please add an explanation why it is your favorite.
My favourite manga is Tokyo Ghoul due to the blood gore and the pain the protagonist goes through to transform into something or someone new. The pain that he gets it makes him feel alive just like when I feel pain I feel alive. I feel similar to him in many ways.