it depends what you mean by sound quality, overall output or the quality of the packaged instruments and effects.

the bundled fruity fx are basic but get the job done but once you start getting your head around this area youl probobly want to bring in some higher quality plug ins which is not a problem with fruity as it has full vst support, Reason is marketed as an all in one software studio so your limited to the instruments that it comes with (unless you marry it with cubase but i think thatd be getting far to complicated right now)

i dont think your going to notice any sound quality difference between reason and fruity loops apart from the differences in the instruments and fx they are using, the actual quality when mixed down to .wav will be the same.

if i were you id concentrate on using fruity loops now as it will probobly allow you to get access to the kinda of sounds your after easyer with all the vst synth banks floating about right now.