ProZ is correct, flat black will hide some, gloss black will actually accentuate any imperfections. The problem with flat black is that it will really show up smudges and other road crud and is hard to clean.
Cooler colors like light blues and greens hide dirt and dents better.
I always liked the sinister look of flat black jobs, but they are a bear to keep looking good. I painted the hood and trunk lid of my 340 Challenger flat black with the rest of the car done in gunmetal grey metalflake and some pigeons from the building next door got happy and celebrated the nice job....