Qualities I like:

-Non-mushy. None of that "oh i love you blah blah blah"
-Kind of emo look. Medium to long length hair. Dark.
-If there's sex, during sex he doesn't get all into it. He's in control, doesn't show emotions often, etc.
-Either mean to the uke, or mixed feelings (you can't tell what he's thinking, but could be mean)

Uke can be whatever.

Examples:

Shiki from Togainu no chi
Sawatari from Interval
Keito from Koyoi wa kimi to chi no Kiss wo
Kuraki from Escape (KYUUGOU)
Mookyul from Totally Captivated

From non-BL: (not saying they're semes, but if they were, they have the qualities I would look for in one)

Sasuke from Naruto
Sebastian from Kuroshitsuji

What I don't like in semes:

-Chasing after the uke all the time (it's fine after certain circumstances)
-glasses (I think glasses just make BL characters look like creepy perverts)

Overall manga should have a plot, if not, I suppose that's fine. Really liked Togainu no chi because I read the story for a bit first, then when I read the yaoi side stories, it made everything better cause there was a background story. But preferably there will be yaoi in the main story, and main story has a plot. It gets kind of irritating how artists just focus on romance without creating a universe or even other problems that come up in life. (i.e, whole story is about seme and uke's love drama, chapter after chapter) I like when the seme leaves the story for the few chapters. So perhaps a fantasy/sci-fi manga?

I think you might like Aijin Incubus. And maybe Deep Bloody Night? ...Neither have much plot though.

I'm going to stick around and see what other people recomend. It is a good request!

[color=blue]THE SOUND OF THE OCEAN IS DEAD
[/color][color=gray]IT'S JUST THE ECHO OF THE BLOOD IN YOUR HEAD[/color]

Summit's Han sae is totally like mookul from Totally Captiavted.
The sterm, built man. you know who's in charge.

"Ok, i decided, i like you, so let's get on with sex."
"but! we're both guys!"
"doesn't matter, you have to move on with your life you know, now onto the bed."
"NOOOO"

Thank you. I read Deep Bloody Night the other day. Aijin Incubus I've read before. Seme was great but the story was so freaking weird.

Re-read the summit today. I love that. But it's licensed and only the first volume is out. D:

Keep em coming. I'll try to add more titles as well. I never remember them offhand, usually.

Thanks for the suggestions so far!