A lot of it just comes down to personal preference. I have fairly weak ankles from multiple sprains from my football and basketball days, so I generally prefer stiff boots and usually pair them with a binding that's a little on the soft side for the board. That's what works best for me, but I'm not sure that I'd necessarily recommend it for others.
"People say that marijuana smoking is going to get in the way of my career. I say to them that on the contrary, my fighting career is getting in the way of my marijuana smoking." -Nick Diaz