Of the ones I've read, I'd like to highlight the really great ones given:
3 AM Dangerous Zone Cat Street Cousin Spice and Wolf Solanin: His other works are even more amazing, if slightly darker. 14-sai no Koi : This one is so cute IS - Otoko demo Onna demo Nai Sei SHIMURA Takako: Writes great manga overall
I've been meaning to read Hotman for a while, but I haven't gotten around to it
And I'll also definitely check out the rest.
@ Seijurou: Some shounen are great, but as a whole I avoid shounen because they seem pretty contrived and unrealistic to me. (to be fair, shoujo can be equally contrived). The characters seem over the top, I dislike harem and absurd sexual situations without a plot to back it up. It's all about personal taste.
I also remembered another one: Tonari no Kaibutsu-kun: Shizuku is THE BEST heroine of ALL TIME. ALL TIME. (Or any 15 minute interval)