It's quite a hassle to keep track of charged and uncharged batteries if you're relying on the power to get you through your next Project. I’ve been using these Sanyo Eneloops for years, and they are by far the best Rechargeable batteries i've ever used. Normally rechargeable batteries aren't recommended in certain devices, and if left for just a short period of time, they lose power. Sure you can wait 4-8 hours recharging them to use them again, but in a few weeks (without using them) they will still lose power.
The Sanyo Eneloops are designed to be a different type of rechargeable and can even maintain up to 90% of their charge if sitting for up to 1 Year!. I've never tried that claim, but i've never had a problem with dead batteries either. They can run a bit high in retail stores, but Amazon and B&H both have some of the cheapest prices for these Eneloops.