Well, let's see...
I haven't read a whole lot of manga, but I've been watching a lot of animé lately. So I can pull some examples from there.
http://images3.wikia.nocookie.net/__cb20121030195709/dragonball/images/thumb/5/5b/Gokusteppingoutofaspaceship.jpg/250px-Gokusteppingoutofaspaceship.jpg
What can I say about this guy? He's become for animé what Mario has been for videogames. What makes this dude so special is that he's such a genuinely nice guy. Seriously! How often do you see action animé protagonists that don't have a tendency to get angry a lot and mistreat decent people? But he's certainly no pushover! A really kindhearted, noble, considerate, awesome dudeguy with plenty of integrity. What's not to like about Goku?
http://fc02.deviantart.net/fs70/f/2012/285/a/a/mizore_shirayuki_by_wrath_and_wesley-d5hmc36.jpg
Oh, dear. This one's a bit tricky... Considering the fact that she hides a lot and speaks quietly, you'd think she's shy, right? WRONG! She hides because she stalks very stealthily, popping up when you least expect her to. Plus, she has a tendency to quietly say something really freaky with a straight face. However, she can also be very sweet... sometimes. In fact, Mizore is definitely the "different" one among her close group of friends. She can be a bit socially-awkward quite often but can tend to bring her own flare and vision to... stuff. (Watch the curry zombie episode, I guess...) I can relate and identify with this character a lot.
http://kingwallpapers.com/wallpapers/lucy___elfen_lied_wallpaper_4-1152x864.jpg
Lucy... this character... this series... Whoa. I guess I'll just say "Lucy" since I suppose that's the "main" personality. (And yes those are horns sticking out of her head.) I say this because she gets this split personality early on in the story. Lucy was locked away in a laboratory sometime during her childhood and escaped several years later after using her vectors (long invisible arms of death) to kill every armed guard who stood in her way and block every bullet that came for her. Though when she failed to correctly deflect a sniper bullet to the head, she developed an adorable and helpless personality named "Nyu", because that's all she could say. Lucy is very complicated and the very center of the big WHATTHEHECKISHAPPENING that is found in what has got to be the most amazing narrative I have ever experienced.
http://wallpapers.animexa.ru/elfen_lied/2200x1239/1024.jpg
Talaris said:
Well there's so many to choose from, so to narrow it down I try and think of one character who alone makes the manga.
This lass instantly comes to mind...
I have no idea who that is, yet she already scares me. And I like
Lucy. Have you seen what she does to people she doesn't like?
https://www.youtube.com/watch?v=cJz1YsnIwaw