Rohloff 

We believe that, at present, Rohloff have built the most efficient and performant internal gear hub. It has a working efficiency of  95 to 99% and 14 effective gears (no overlapping gears).
 There is a very even increase in gear ratios. Meaning that it is always possible to find the optimum gear for all riding situations.  From the 1st gear to the 14th there is a 526% difference in range and each step in very progressive.
You can shift from gear to gear or jump several gears in just one simple turn. Changing gears whilst stationary is also possible
The gears are fully encapsulated in an oil bath which only needs to be changed after 5000km or a full year.