Roofing Safety

Wanted to do a quick poll on roofing. When I was a roofer in college, I know wearing boots on roofs was a big NONO because the boots can damage the shingles. We always wore tennis shoes to avoid damaging the shingles. The previous safety director required boots though because of nails even though nails can go through boots also. What does your company allow the roofers to wear? Boots or Tennis Shoes? If your company doesn't do roofing but still have an opinion, what do you think roofers should wear?