My opinion are to get a IGH with one sprocket rear and one chainring in the front. Are you sure you need more gears than you get from a Nexus 7? (said to be better than the Nexus 8). If so go for the Rohloff. It is better to spend the money than doing this 2-3 times without being happy with it.
I like the Nexus for many reasons, but most of all for the clean cable line with no clickbox.