I have read very few completed manga, and they have all been shoujo (Ouran Highschool Host Cub, Special A, Tomodatchi) with the exception of Full Metal Alchemist. Almost all of the manga I read are ongoing and usually shonen (I don't read much shoujo to begin with. Hard to find decent characters and an appealing storyline.)

Most of the manga I read are mostly ongoing and I don't think I've read any completed manga as of yet.

I've read only 3 mangas till now and all these are ongoing!

Most of the manga I read are still ongoing, but I have read a few completed manga series as well.

the main reason is that the compleated ones i can read in like 1 day if i want xD

I don't like ongoing... Like, I hate waiting for bleach because the chapters are soo short! I just lose the rush I had! I kind of lose interest! If I read complete then it keeps me all exited!

I have like 70 ongoing and maybe 120 completed or something =P

Most of the manga i read are still ongoing but Majority of it are completed now

Only four of the series that I'm reading now are still ongoing (Magi, Yotsuba&!, Melancholy of Suzumiya Haruhi-chan and Disappearance of Nagato Yuki-chan). The rest of the series that I'm still or finished reading are completed (Negima, Me and My Brothers, Fruits Basket, Azumanga Daioh, 20th Century Boys and Pluto)