To be honest, I liked the doujin more. The boy was more asthetically pleasing and his awkwardness felt more relatable for me. I find the difficulties and differences existing between humans and the monsters really interesting. These somewhat vanish if the main character is a monster himself.
Also the way the oni and dwarf were related seems shallow and cheap. I find the slow -- and somewhat awkward -- development of love more interesting, than setting them out as childhood friends and calling it a day.
My recommendation: Read the doujin, I thinks it's better and "fluffier"