1 deatnote: very good manga. I prefered the anime though because of the atmosphere. I suggest seeing the anime.
2 naruto: the most famous manga around the internet. DO NOT WATCH THE ANIME.
3 one piece: big world. Funny world. Cool protagonists and... pirates. What else?
4 bleach: superb manga for those that like sword fighting with magical creatures.
5 hellsing: the best in its kind. The anime though for the fights is better.
6 vk: i do not suggest reading it, but i really liked it.
7 liar game: Excellent manga but you do not understand anything.
8 d.gray man: good manga that is liked a lot by many.
9 clay more : decent manga bad illustrated though(in my opinion)
10 deathnote: yeah i know that i have put it first. I just really liked it that i have to put it at least two times in a top ten list.