For some time I’ve used "eneloop" rechargeable AA cells manufactured by Sanyo because they come fully charged and have a very long "shelf life". In other words, once charged, they remain charged – unlike most. They actually lose about 20% charge per year, which is pretty good.
However, I came across a YouTube video which led me to IKEA "LADDA 2450" cells. It turns out that these are "eneloop" in disguise and half the price!