I bought quilt pencils about a month ago. Because the lead inside they are very brittle and it keeps breaking out, sometimes before you can even get a sharpened point on them. My pack had yellow (which is great on red), white, and grey, and they have all been sharpened to small little stubbies. I don't know what a better is, but I'd like my marking device to last me more than one quilt. Oh and you have to mark it a couple of times for it to be dark enough to see. A friend warned me that she had that trouble with them years ago, I would have thought they would have fixed the flaw but no.
My pencils had erasers on the ends, and that took the marks of no problems. It's supposed to come off in water too, but I haven't washed it yet.
Hope you have better luck! :)