I use FL with the Massive plugin, which adds a lot to it, especially if you want Skrillex-style wubz (Skrillex uses Massive as a stand-alone with a MIDI) or to make you're own wubwub for a dubstep song. I also use the Toxic Biohazard that come with FL for certain keyboard sounds for trance and rave songs. You can make plenty of nice tracks JUST with FL, but I can also see why you would want to use other programs.