IMO your choice depends entirely on your power needs. If all you want is to charge 2AA's for your camera and 3 AAA's for your light and you're reasonably sure of a steady supply of sunlight, go for the 2AA model. I have a 2AA Canon camera and I would have to take a huge amount of pictures with flash and review to require recharged cells every day. And my 3xAAA light only requires recharging every 3-5 days with moderate use. But as always YMMY.
But if you're not counting ounces or pennies and/or you plan to consume more power in the future, go with the 4AA. And if your source of sunlight is questionable, the 4AA gathers photons twice as fast which could be a huge advantage on cloudy days, deep canyons or shaded forests.
I've been toying with solar charging for several years and honestly, unless you're going to be out there for a long time, simply carrying extra cells (especially lithium AA's and AAA's)is simpler, lighter, more dependable and certainly cheaper than a charger.