... With a stainless steel bolt. If you are leaving fixed iron in the rock for an anchor, do it right, please. No sense replacing it with another pin that is just going to rot out again and become dangerous.
As far as I am concerned, unless dealing with an emergency situation, all fixed anchors should be good quality bolts. They are safer, usually less obtrusive and can be placed in the best spot and don't affect the actual part of the rock you are using to climb (filling cracks or altering their natural shape)