I know the manga "My boyfriend is a vampire", it's really nice.
I don't know the other two, but I believe they're good mangas too, so I'm going to add them to my list! :)
Recently I started reading "Dear My Girls", it's really cute, I love the art! ^_^
Hum... that's hard to tell one because I like many of them. But if I really have to choose one... I would have to say CLAMP. I like both the stories and drawings. :)
But I would feel bad for not refering Natsuki Takaya (Fruits Basket) and also the mangaka of Dear My Girls :)