Sanyo Eneloop batteries are probably the best rechargeable batteries on the market. They keep their charge literally for years, come precharged, and have up to 1800 life cycles. They are available in AA and AA sizes. However, you can put an AA inside their C and D adapters.
No doubt, the best batteries I’ve used are Sanyo’s Eneloop cells. They’re NiMH but the self-discharge problem is pretty well licked, and Sanyo are the ones who solved the problem.
Eneloops are still the best, but there are more makers now of LSD (Low Self-Discharge) NiMH cells. Usually marketed as “ready to use”, their initial charge should still be available at time of purchase.
The Sanyo EneLoop rechargeable battery could possibly be the best rechargeable battery on the market at any price. When you use the AA Sanyo EneLoop batteries and the C & D cell adapters you can convert the AA batteries into C & D cell sizes. One great feature of the EneLoop is the slow discharge. That means you can charge them once and leave them in the drawer and months later they are still usable.