Once again, it depends entirely on what you want to do, and how much you already know.
Fruityloops is a good bet, as it is (comparitively) easy to learn from scratch, and as long as your happy being restricted to electronica.
Most (all) of the other software is developed more for a theory-based recording. While FL can handle piano rolls and the same meathods, due to the fact it takes a lot of purchased and free add ons to make it produce anything other than electronica isnt worth the effort. If you want to do somthing lighter, such as orchesteral, reason is the way to go. Its a LOT harder to learn, but it does teach you how to use modules in real life as well as on the software, meaning you can use what you learn from it practicaly.
As always, i'll suggest that before you get any production tools, to find a cheap midi arranger like cubase VST to play about with. ALL music software, Fruityloops included has a piano roll that works using MIDI, and understanding how to produce and lay out music on a midi sequencer will give you a huge boost up the rungs of the musical ladder.