If you are comparing conte to vine charcoal, then obviously conte. I get the feeling more are, which is an unfair comparison considering vine charcoal is sort of the mspaint of the traditional world. Its simple but in most hands will produce an ugly mess and awful amateurish results.
Conte is a slower waxy version of compressed charcoal (and man do i hate waxy, don't even ask me how I feel about 'art sticks'). Compressed smears less than vine charcoal but a bit more than conte so less tidy people tend to make a mess out of themselves.
I may be slow at drawing, but its because I take my time to do stuff right and pay attention to the media, I don't need the media itself slowing me down and prefer something that can keep up if i decide to work faster, conte doesn't provide that needed speed so its compressed charcoal for me.