I'd steer clear of FLStudio as the whole company behind it reeks of unprofessionalism. You can see what they think about Mac OS on
their own support pages. When I wrote to them about it, saying I would try it in VPC, but would probably not buy it, I was accused of piracy.
I'd say go with Garageband, or Reason if you want something more. Or you can use both, since they both support the ReWire technology!