Deppends what your wanting to do. Active speakers offere easy installation. However, they are also usually a compromise and you don't get the quality that you might get out of a seperate amp+speaker combination. Plus having you own amps means its easier to change an amp if it blows during the night. Also passive systems mean you can have all your amps and compressors etc... in the same rack making the sound engineers job a lot easier.

If its only a small rig, then active could be the better option, but for large rigs, then passive are deffinately the way forward.