I prefer earlier versions of Reason. 6.5 is cool, but cluttering. I like the ability to record now, but it comes at the price of a cluttered workflow.
Just my opinion, FL is the BEST production software on the market as far as overall functionality. It does everything with ease. Sampling, sequencing, if anything the unorthodox look of the mixer could be it's one soft spot, but anyone who's used it once or twice can quickly get used to the look, still works like any other mixer.
I still like the "all in one" idea of Reason though. Best way I can explain it is Reason is a substitiute for a Workstation Keyboard, FL is more of a Drum Machine/sampler/Sequencer centered to whatever else you add using vstis.
Reason IMO challenges me to work smarter which results in more creativity while FL is more of a "routine" production tool(referring to myself personally). Plus I'm on a Mac, and hate all the hassle of running a windows environment just to use FL, so Reasoon get's my vote by a hair.