I like 100% DEET only in the tiny containers I carry in my kit, because in an emergency, I want enough to go around in a small package.

Excessive DEET on my skin sometimes makes me feel ill and dissolves the finish on my gun and burns into the lenses of my glasses.

When I use a standard spray can for everyday outdoor hiking/fishing etc, I use 40% DEET on my hat and shirt. If I have long pants on, I spray some on my pant cuffs and socks to ward off ticks.