Which do you prefer, original manga/manhwa story or doujinshi?

Originals. Doujinshi are self-published, so there are originals out there, but they are generally fanworks.

Originals. But only because the only doujinshi I've seen are practically pure porn ╮(￣▽￣)╭

Personally, I prefer originals over fan doujinshi because I like sticking to canon. Once I go off-canon, it ruins the original story too*, and no longer feels like the same work.

*(I don't mean it ruins the original because it's necessarily bad, I just mean it changes my feelings and perspective of the original and makes it less enjoyable or even dissatisfying.)

I like, though, doujins by the original creator/s because they just feel like bonus stories.

Hahaha! Me too. And I love when my favorite anime characters get all hot and sexy during sex scene tho. Especially Erin and Levi. ლ(´ڡ`ლ)