Since black goes with everything, almost any colour of pants would look good with a black top. White would look especially good because of the bold contrast in edgy or fashion forward looks. Normal blue jeans would look good for a casual look. Purple or red would look good for an emo/rocker look. If you wanna take a really big risk and go neon, then green would be a hot colour. I’d stay away from pants straying into oranges and yellow because those look clown-y and brown pants can be very boring.