I'm not familiar with reflex, but I think a guy I know is using it an likes it.
Oh, FS One is the one that my cousins have, it comes with a controller. I didn't like it as much as RealFlight but I didn't think it was bad.
Yes, I would suggest a 6ch controller, will be a better match to flying real models.
Why am I the only one answering these questions? I know there are other people here who have used various sims and are probably more qualified than me, where are you guys!?
You should probably do a search here, I think many of these sims have been discussed a few times here already.