If you’re looking for rechargeable batteries, Sanyo Eneloops are the undisputed champs. Look at all these great reviews. You can find them on RedFlagDeals from Dell every once in a while. I don’t use anything else.
edit: Aaron suggests considering the higher capacity Eneloop XX. There is also a lite line for low power devices, so the new bottom line is to get Eneloops of the appropriate rating as per your application. Check the official site.