Staz-on is not meant to be used on fabric. It states that on the pad directions. It can be used on leather, however.
Versacraft is made to be used on fabric. It needs to be heat set after stamping to work properly. I don't know how well it holds up over time. I know there is a thread discussing fabric somewhere on Splitcoast. Perhaps you could find it by performing a search.
I am still looking for a good way to color on fabric. I would like to stamp a design on tea towels and then color the design. I bought fabric markers, but they did not stay color fast at all. Does anyone have any suggestions?