I used to love William Petersen's looks. The lead on CSI for many years. I had seen him in movies when he was younger (so was I) and developed a crush on him. But now, not so much.
My favorite tv actor now, as far as looks go, is Tom Sellack.
He's as good looking as ever, and he was ALWAYS great looking!
Someone else mentioned Edward Norton, an odd choice I thought. But now that he's out there, I realize that he is also one of my favorites. He doesn't have outlandish looks, but he gets to you. I think it's his acting style. 8-)