I got a question about Kare Kano, aka Kareshi to Kanajo no Jijo or His and Her Circumstances. It's hard to recommend shoujo comics like Kare Kano - and Kare Kano is so very, very shoujo - without knowing the tastes of the audience in question.
Kare Kano is a very popular girl's romance comic in Japan; the wildman director of the anime industry, Gainax's Hideaki Anno, adopted it into a flawed but brilliant TV series of the same name, which is available in the US from the Right Stuf. Like other shoujo manga which have been adopted into popular series (Marmalade Boy, Kodomo no Omocha aka Child's Toy), watching the anime before the manga may drain a lot of the fun out of the experience of reading said manga. I certainly found that to be the case with Marmalade Boy. Personally, I've been enjoying the US release of the Kare Kano manga. But your mileage may vary.
Yukino Miyazawa is a brilliant, athletic, kind, generous, popular high school freshman. She's also an egotistical, monstrous fraud, who delights in fooling the world into believing that she's the perfect self she's built in her own image. She's a lot of fun as a protagonist, even after the love interest figures her game out, and the fraud comes out in the open. The love interest, Souichiro Arima, is similarly self-invented, if somewhat more tortured about this falseness.
The A plot doesn't last very long in either the anime or the manga, and generally behaves like a bad case of malaria - going into remission for long periods, only to come back viciously. While the A plot is in remission, various B plots about the swarms of secondary characters chug along in an amusing fashion. Both versions bear more resemblance to a good-humored, sprawling Victorian novel than the usual run of soap opera or romance-comic intrigue. Think Middlemarch.
The anime is probably a little darker, mostly due to Anno's massive personal issues. But the anime is also a much denser text than the manga, and directly incorporates large chunks of comics imagery directly from the manga. The anime is strongly experimental in ways that the manga simply isn't. On the other hand, the manga is a mildly impressive exercise in high shoujo formalism in and of itself. It's this aesthetic quality that's held my interest in the Tokyo Pop GNs, whereas the more utilitarian, plot-oriented Marmalade Boy failed to retain my attention.
For at least one friend of mine, the main reason to look into the Kare Kano manga is because of the incomplete state of the anime - he wants to know how the story ends. Anno was dumb enough to jump into a project when the material wasn't sufficient for the half-year season he had committed to, and tried to pad things out by animating every single part of the manga story, including a long-running arc called "14 Days" which *hadn't been finished at the time Anno was working*. The anime gets, like, five days into the "14 Days" and just calls an end to the series, leaving the audience seriously in the lurch. It's a large part of why I call the anime a failed masterpiece.