I'd say this is my favorite manga of all time, but there's one other just about like this that suprasses it for me. I'll explain later.

I just love these 'forbidden love' stories. Love that should not be, but against odds it's there. A creature horrific and shunned, but touched by a smaller, often more fragile soul.
However in this story the specific 'creature' is very powerful and also respected at some parts. But still, he is the thorn mage, still somewhat belittled and unholy in other eyes. But Chise knows better, she knows how to find that heart.

and that's what I love more about stories than most of the other popular Shonen anime/manga out there. The concept is simple, but misundertood a lot. For me its more powerful of story telling because of that.

This is my favorite Anime of all time, but not my favorite manga by one other manga out there. It is the manga which the Ancient Magus Bride was inspired by. And if you like this manga/anime, I highly recommend reading "The Girl From The Other Side" , by narrator and illustrator Nagabe.
For me, this story means a lot and every book touches me. As I said the magus bride was inspired by it, so the story concept is very close, but yet very different too. I won't spoil more, but I'm sure you'd like it too.