kaze no sakura
Sesshoumaru isn't a so-called "bad-boy". He is a person who can be as compassionate as his father, yet he tends to push it out of view by putting on a cold mask and pretending that he isn't a nice person. I would prefer having a nice person as opposed to a man who is cruel down to the very core of his heart. Sesshoumaru appeals to me as an anime male character because it is obvious that he is not like that at all.
I agree that he is much kinder than he lets on, but I don't agree that he is "not like that at all", which is wonderful, since I love a good debate. We've seen him rip the head off a guy for simply being in his way. The way he treats Rin and Jaken is definitely proof that he's kinder than he wants people to think, but he can be pretty bad when the occassion calls for it--though he seems to be softening up quite a bit since he met Rin. Still, I have to agree, the fact that he's not the bad boy he pretends to be makes him an awesome character. Oh, but that doesn't fully answer the question. For anime/manga characters, I like both--bad boys and nice guys--but for real boys it's all nice guys.