Reading this thread, I'm now unsure if 'the c-word' is referring to **** or cracker. This is why it's better to actually write the words down, to avoid confusion. I don't really understand why people are so loathe to do so, for the purposes of defining an argument, I'd say it's perfectly acceptable to actually say what it is you want to discuss. For the purposes of this reply, I'm going to assume 'the c-word' is ****. And also that 'the n-word' is ******.
I would be inclined to say that **** is more offensive, as any person of any race or sex could be offended by it, whereas ****** is generally only offensive to black people. So by simple maths, **** would seem to be more offensive. But then, I would actually consider ****** to be more offensive because it's a specific racial slur, whereas **** can be used against anyone, like I said. So actually my maths have turned against me. I'm going to say that ****** is more offensive.
That being said, I have a problem with the fact that ****** is only offensive if a white person says it. Plenty of black musicians and comedians regularly use the word ****** with seemingly no repercussions, yet if a white person were to sing along to one such song, they would not be very popular for it. So that leads me to believe that it can't be all that offensive.
I don't know. I think the important thing is context, and how the word is used. If someone is singing along to a song and uses either word, I don't think that they should be construed as offensive, because they are not being used in an offensive manner, nor are they directed at a particular person. If they are used in a derogatory or insulting manner towards a specific person/group of people, then I think that both can be very offensive. At the end of the day, they are but words, so it's however much stock people want to place in them, and it's then up to them how much offense they want to take.
EDIT: So I'll say that they can be equally offensive, depending on the target.