I used to use black, but it is so damn messy.
red is really permanent too.
I framed a basement development one time, layed out with red.
2 or 3 weeks later just before the carpet was installed, there was a flood.
A big one, like 3 feet of water in the basement.

ever see titanic? The water was crystal clear.
This was caused by an over zealous city guy turning on the water to the wrong house (our meter wasn't installed yet) aparently he turned it on at 4 pm and water flowed full blast for about 16 hours. And the drain was partially blocked with something, or drywall scraps or something.
Anyway the insurance company paid for a complete gut, and redo.
After all was removed and swept and dried, I was able to use most of the original chalk lines.