I ride Fuels & rally's (and used some RPM's too): The rally has way more Low end and will help you upwind better. Unhooked tricks with the Rally are possible, but to get a nice slack, there is no better (slingshot) kite than the Fuel.
For me: Rally for waveriding (also unhooked when depowered properly), Fuel for freestyle. I never fancied the RPM, it is not bad, but for me it is not the ideal kite. If you want a freeride kite that can unhook: either RPM or Rally, with the RPM having a bit better freestyle characteristics and the Rally having better wave characteristics, better low end and slightly better range.
Very nicely put, absolutely spot on. The rally is my fave due to above. Fuel is so underestimated now the RPM is out.