It's mostly all about the characters for me. I've read some pretty straight-forward/predictable/unoriginal manga before, but I still loved them because the characters were so great. If the characters are flat or annoying, I give up on the manga pretty quickly.

Of course, art is a big draw for me too. I want to look at something pretty and that's easy to follow, not a giant clusterfuck of sketches.

yea for me manga just impresses me because it's black and white but the tones and effects the mangakas use make it look so amazing.Also I like how you don't have to worry about fillers in manga,it goes straightforward with the story.Also it goes more in depth and doesn't skip over events like alot of animes do,same with the endings finish in maga on series like Inu-Yasha,Tenjou Tenge,Blue Exorcist,etc.

Art Style: This is actually not my first criterion when looking at a Manga. The majority of Mangakas draw just fine and I don't exactly care too much about the art. For example, Angel Densetsu had probably one of the most ugliest art I have seen, but I still thoroughly enjoyed the series. If the series has good art, it can certainly increase my enjoyment but in the end it is not a make it or break it deal breaker.

Story: This is actually more important to me than art. If the series has a good story, good arcs and conflicts, then I am instantly hooked. An example of a series that really shines in this area is Great Teacher Onizuka. A series that I hate and that fails in this area is To-Love-Ru.

Characters: Just as important as plot, the characters must be interesting not only in appearance but in their personalities and interactions.

Age groups: I usually read Shounen or Seinen (about 80% of everything I read are these two categories)
Shoujo I am always willing to try, in fact two of my favorite series are Shoujo (Kaichou wa Maid-Sama! and Boku no Hatsukoi wo Kimi ni Sasagu)
I never read Josei.

Genre(s): My favorite genre is Romance period. Harems are my next favorite, but I have yet to read a "good" harem manga other than Rosario + Vampire. If the series at least has a hint of romance, then I will definitely give it a try. Other genres are important to me also if it has drama, mystery, action, etc.

Art style is very important to me, I can't really see myself reading any manga with less than average quality art.
Stories are also very important, I don't know how many typical manga there are, but I always try to find the more unique stories, with characters and plots that aren't the norm.
Genres, I'm really open to anything, but I usually lean towards things that have a good balance of drama and comedy. I do like reading some all comedy manga, but almost never any all drama.
Also, conclusive endings, that's always a good thing when comes to reading a manga.

Definitely the story! But if the art looks really shitty or just bugs me, I wont be able to make it through the whole manga. The genre, hmm I guess I can get into pretty much anything. I'd prefer if it had romance, but sometimes the story is just too good that I'll love it even if it doesn't have romance like Liar Game. But that's a rare exception.

fine chicks and requires zero brain power

For me it is always the cover arts, I just love to spend a few minutes on the covers of the mangas before I dive into them :D

definitely the art... story is just secondary to me

Boredom and if I got tired watching Anime.

Uhmmm... the storyline and sometimes the drawings

First, the anime. in generally said, the anime follows the manga, while i finish the anime, and do not feel enough, so i go to read the manga.
well, another, the story is the main element that i go to read the manga.
the art style is the second element

manga

Cool art. Interesting story.

Usually the art and the story.

A quality cover will draw me in, but usually they have really bad story lines.

The majority is the art and then the storyline ^^