Ultimately it depends what your shooting objectives are but I bought the Spot (and may buy more) because I'd rather have stronger light, target it, soften it with diffusion, keep spill under control.
If I were buying just one light, I'd get the spot. Brighter and more versatile, since you can always diffuse or bounce it. For a more complete interview set, I'd probably buy two spots and one flood. (Hey, I just did that!)
In the most recent review on his website, Erik Naso speculates that the flood may work better with the newly introduced Aputure softbox/grid because it "fills" more of the area of the diffusion material and will therefore create a softer light in a smaller package. But if you're not set on using that particular kit for diffusion, there are plenty of other ways to make the spot version look softer. (Sorry, Erik, if I misrepresented your findings.)
