Berserk, Giganto Makhia Recommendations
Both are about fantasy worlds populated by humans as well as ghastly monsters, the lone hero and his magical companion battles against impossible odds, taking on the gargantuan monsters in direct combat.
Both manga are written by Kentaro Miura, so they share many elements. They both have a strong, male protagonist, who travels with a magical companion. Both manga are set in a fantastical world filled with monsters and strange creatures. Also, in both manga, the protagonist ends up fighting gargantuan monsters. Overall, they have a similar vibe.