Do you prefer hentai doujinshi or hentai manga?

Both are good. Though the best one of all is still Visual Novels!!!

what is diffrence?

It varies depending on a myriad of factors such as art quality, dialogue and what the actual eroge scenes entail.

Doujinshi are self published works, mostly revolving around anime/manga/game series with pre established characters put in a situation. It doesn't have to be, the most important thing is it's a self published title, so it could be original content - but people know them best for relating to series.

Hentai manga tend to be an entire volume long and can extend to multiple volumes. They're published by a publisher.

Examples:

Doujinshi:
Link (Based off of Puella Magi Madoka Magica)
Link (original story, but self published)

Hentai Manga:
Velvet Kiss (Multiple volumes long, original story, published by Takeshobo but not to be confused by the mangaka Harumi Chihiro.)
Ring x Mama (Multiple volumes long, original story, published by Takeshobo but not to be confused with by the mangaka Manabe Joji.)

The publishers are the ones who plan, edit, market, and distribute the manga to different stores. You can look at the spine of the book and see who published it plus the credit pages in the back of the book.

i prefer mangas because alot of times in doujins character personalities are changed to fit the desired storyline.

Tough choice.

I like Doujins if I fancy a short-but-sweet "original" story (usually a few chapters long) but you do get some good ones out there with nice artwork.

But Mangas tend to have better overall artwork and much better stories, not to mention that they last longer.

I like the two but I more prefer hentai manga.....

i would say manga, given the current trend of touhou doujins swamping c81. i have nothing against touhou, but a convention comprising of 70% touhou doujin is utterly ridiculous.

The big Toranoana doujinshi store in Japan (several stories high of doujinshi and what not) has an entire floor dedicated to Touhou doujinshi. Fact :O

I prefer doujinshi, most of the good series on fakku are usually doujinshis

when it comes to doujinshi its basically a hit or miss. and depending on what characters is put with who, how it is done and how the story is portray has a big hand in it too. i can say there are a few doujinshi that are good but there are just some i wish didn't exist and ruin the image of the anime/manga i fell in love with the first time.

my opinion anyway :P

I find there are more hot Doujinshis that I like reading than hentai mangas, however the mangas that I do find are usually of high quality since they have to establish the characters and a story, as oppose to the Doujinshi which, using pre-existing characters and settings, simply focuses on sex... so in the end it's a coin toss I guess.

My vote is for manga, just cause the artists sometimes fucks the original design and sometimes make it look even better. Its random. So if I had to choose, I choose manga.

I like manga the best but i do enjoy a good doujinshi

I prefer manga. Doujin artwork never seems to live up to my expectations except in a few cases. And I like the story in mangas.

I prefer hentai mangas with good stories because I like to cry masculine tears of joy as I fap.

I prefer hentai manga because, generally, the manga tend to have a more solid story. And I know what you're thinking, "a story in hentai?" But to me, if it's just mindless sex or whatnot, it's not very good and won't do much for me. Plus, for the doujinshi, I'm a bit picky because if I'm a fan of a series, say Bleach for example, and the personalities aren't the same, like if a doujinshi had Orihime being arrogant or something, it just annoys me. Also, if the artwork isn't close to the original, it also annoys me.

I like manga when they have an interesting story and hot sex scenes... But I also like seeing the characters from series I love getting it on with each other.

I voted for doujinshi mainly because of the Rei series from Mogudan (yeah, some of you may not get it, but that's hot for me)... so yeah

I do enjoy my doujinshi, but manga isn't constrained to already established characters.