I prefer to paint the backs of my tanks black. It really does not matter what paint you use as long as it is coated well, usually several light coats versus one thicker coat which tends to run and streak.
I have used Krylon in both a spray paint and brushed or rolled on from a can. I have also used no name or store brand paints and the worked just as well. I usually mask the trim off but it really does not matter.

Just be careful with hang on back devices like skimmers, overflows and HOB filters as they will scratch the paint if moved around a lot. I sometimes stick a small piece of felt on the contact points and that seems to work well. Its easy to touch the paint up though if it gets scratched, a dab on a paper towel goes on easy and requires no clean up.