Since our band shared the practice field with the football team the coaches suggested we use the same type of paint they used for yard line marking. We discovered the supplier had several colors available. Since the field was mowed at least once a week our marching spots were "erased" pretty quickly. I liked that we had the learning crutches removed so we could paint new drill spots often. Someone suggested regular paint to be more visual and have a greater variety of colors but I was told it was toxic and it could harm football players when tackled (making face plants).
On asphalt parking lot fields I've used the regular sprays but of course they are more permanent and if we have too many sets in our show I run out of colors. Sticker dots are nice because they can be scraped off when desired, and each band member's number can be written on the dots. I've tried poker chips but I've never had enough time to make them effective for my rehearsals. To each his own.