I’m a huge fan of “porn with plot” stories, especially manga. I’ve been reading Nana to Kaoru and Sundome, neither of them is porn but still go beyond ecchi.
Recently I read a hentai manga, by Yamatogawa, called Aqua Bless. While it doesn’t have a memorable plot or interesting characters, it’s really funny, well-drawn and with a huge variety of stories.
It has 10 different unrelated stories (though in the end there’s a short full-color comic linking them all), with many different characters and settings, all of them involving full-on explicit sex. Young inexperienced couples, twins switching places, fanboys and their idols, fangirls and their sempais, dommy tsunderes, shy girls with glasses, exhibitionism, crossdressing, threesomes, there’s something for everybody. It’s all heterosexual though, aside from the ocassional yuri chapter.
My only complaint is when the sex is non-con, but thankfully it doesn’t happen often (which is saying a lot considering the genre). Also that everybody call out their orgasms. XD