LAers use many marking utensils for, well, marking and they all have their favorites. i love a simple little chaco-liner. i use two colors: white and yellow. i don't use blue because it has a reputation of not removing completely and staining. i also use the Magic chalk in a pounce pad. magic chalk is water and steam removable. i also use a light hand with the chalk- i don't need it to be seen from across the room, i just need enough to see while i'm quilting.
i've always been a bit apprehensive to use any kind of marker pen (water soluble, air erasable) because i never know what happens to quilt after it leaves me. if i do have to use one on a quilt top, i test it on the wrong side of the pieced top on a seam allowance. i have learned the blue water soluble one can be tricky to remove from the paint on white-on-white fabric. the air erasable one is tricky too- with our humidity, the purple line is gone before i'm even done drawing it.
there are numerous ways to remove chalk from a quilt top and i've tried a couple. first, i used a dry Mr Clean Magic Eraser which worked okay...but left a lint looking powder. then i tried a microfiber cloth which kindda did the same thing. then i read somewhere about the 'old fashioned' tried and true red fabric lint remover! i have found my one and only.
i found a well made, good quality made one at Wal-Greens. when shopping for one, look for one where the red sides are slightly convex with the red fabric wrapping slightly around the edges.
a simple swipe (or two) across the fabric and the chalk disappears.
whatever you use, test to make sure the marks remove to your satisfaction!