If you are only interested in energy efficiency, CFL bulbs are more efficient than LEDs. They provide you with more light and consume less energy. And we all know that in off-grid systems it is better and cheaper to save energy than to produce it.
But this energy efficiency should not be the only reason for making this decision. There are other important features to be aware of.
First of all, a typical CFL light bulb requires alternating current (AC) voltage. And to have AC voltage in an isolated system, you need an inverter. The inverter is connected to the battery bank (which only provides direct current (DC) voltage) and produces AC voltage.
It is much easier to use LED lights in off-grid systems, because LEDs also run on direct current. To be more specific, a single LED diode runs on direct current. So you don’t need any expensive hardware (a good inverter won’t be cheap) to run your LED lights from your off-grid systems.
The difference in LED / CFL efficiency is somewhat balanced by the efficiency of the DC -> AC transition in the inverter. This device, unfortunately, is less than 100% efficient. However, the total efficiency of inverter + CFL is higher than for LED light using DC voltage.
CFLs emit light in all directions, while LEDs give a more concentrated beam of light. Because of that, CFL lights work best as primary light sources for entire rooms, while hanging from the ceiling, and LEDs are used to provide light in smaller areas, such as on a single desk. LEDs are often connected in the form of a light bulb (with an Edison screw) that can be installed in a conventional fixture, but can also be connected in the form of LED strips that can be used for hallways or decorative purposes.
As you can see, CFL and LED lights would probably work better in an off-grid system if they were used together.