I'm still searching for the perfect marking tools, too. :)
Don't get "The Ultimate" Quilt Marking pencil. It barely marks on paper, much less a soft quilt - the lead breaks with the faintest of pressure.
I LOVE the Sewline mechanical pencils, all of them show up nicely and all of them have easily brushed off or washed out of my projects.
I also love the Frixion ball point pens and highlighters by Pilot if I'm marking on light-to-medium colored fabrics. The marks disappear with ironing and the ink washes out with a little regular detergent.