In today's electronic world, the best rechargeable battery is normally considered to be one with the lowest discharge, one example being the Uniross Hybrio Ultra, found at the Battery Company.
For low discharge, you may want to take a look at products with Nickel-Metal Hydride (Ni-MH) cells; they also have a strong life charge within them.
The newer type of Ni-MH batteries also come pre-charged and won't deteriorate on the shelf. This is a great step forward compared to the older, alkaline batteries whose shelf life wasn't great.
Other advantages to using Ni-MH batteries over the alkaline enemy is the fact they can be recharged up to a thousand times, and to put the overall life into perspective, they will run up to four times longer on a single charge. Rechargeable batteries are also better for the environment. With the strength to be recharged up to a thousand times, this is far better than the standard, throwaway alkaline batteries.
Other types of rechargeable batteries are Lithium-ion. Also possessing a slow discharge, they are designed for use in high-drain electronics, such as laptops or digital cameras.
For smaller devices, like mobile phones, kindles or an Ipads, a Lithium-poly battery is smaller than the Li-ion and they can last up to 100% longer.
The Infapower range, found at the Battery Company go one step further and pride themselves on their eco-friendly products.
For those seeking a fast power time, the Battery Company recommends the Ansmann range, which boast a fast charge and possess the highest capacity found in a rechargeable battery at this time.
Finally, Camlink, contain no added toxic or hazardous chemicals and suffer no memory effect.
All in all, rechargeable batteries are clearly the way forward, being better for the environment and, most importantly, they are better for your pocket!