okay - for one - mj has various printers not just flashforge.
cura won't work with flashforge machines.
In fact neither will the other two he mentioned either :-)
At least not without a lot of work and a gpx utility of some sort.

simplify3d is the best around - yeah you pay for it - to be honest it's the only software I've actually paid money for in the last 15 years. And yes it's worth the money.
Prints are sharper, cleaner and just better. You have more options than you can shake a lot of sticks at and it's out of the box compatible with ff machines - even with complete usb control.
It's also going to be compatible with any other printer you might get in the future.
But apparently not linux compatible ;-)

The main alternative to rep-g (which is the worst slicer I've ever seen) is makerware desktop.
download links here: http://3dprintboard.com/showthread.p...-x86-computers
Pretty good, easy to use and does produce decent prints.