hm.. a really hard question.. as it is now.. I think either daughter of the nile or one piece..
I'd say one piece if you get to bring the whole serie (^_^)

Tsubasa Reservoir Chronicle

Sailor Moon, Ceres:Celestial Legend, Alice 19th, Gundam Wing, and Immidoki!

vampire knight or absolute boyfriend.. ^^

if comics, then complete series of Pugad Baboy.. ^^

Death Note, One Piece and Detektiv Conan.

My faaaaves.

for me i will choose one piece..that is so freaking funny.. so that i wont get bored..

hayate no gotoku.FTW.

something that was long enough (like naruto, bleach, fullmetal alchemist) to keep me occupied until the rescue come.i also like some comedy in the manga so i don't get deprest while waiting.

a loong manga.

my choices

hana yori dango
skip beat
tokyo crazy paradise
beck
...

Hard to decided...but I think I will choose Junjo Romantica !

I would probably have Fruits Basket with me. It's a perfect blend of romance and comedy, so I would be kept somewhat sane...MAYBE. XD There's no guarantee that manga would keep me entertained enough while being stranded on a deserted island - I would probably also need a sketchbook and some pencils. Lol, drawing keeps me calm and content.

Detective Conan. I could read that for days.

getbackers

OMG that's like murder to me!!! One manga are u kidding!?! There r so many good manga out there that it's soooo hard to choose. But if I really really have to choose....um...............ok I got it! It would be skipbeat! Love Kyoko and Ren plus the story's very funny.

maybe a cooking manga so ill remember good food and that will raise my will to live