Best rechargeable AA batteries?

I have the same rig as Wayne notes. I use it mostly for AAs but also AAAs. Eneloops have worked exceptionally well for use in my Nikon Speed Light flashes, my digital recording device (a Marantz 660), and various flashlights. The LaCrosse recharger unit is great, robust, and allows numerous options for charging, recharging, topping off, etc.

I've had four packs of Eneloops (in the sort of plastic battery carrier devices sold by County Sales or MaxPedition stuffed into the bottom of my camera or recorder go-bags...and pulled them out not remembering when they were last charged...and they worked like a charm.

I'm going to be the dissenter in the ranks, but let me justify it. First -- I will definitely recommend the Maha Powerex branded chargers. I have been using the C9000 for a few years (or it's predecessor) and love it. Simple to use if you want to ignore the buttons, but when you need to you can rematch and renew your sets.

http://www.amazon.com/Maha-Powerex-MH-C9000-WizardOne-Charger-Analyzer/dp/tags-on-product/B000NLUSLM

It also runs from 12V which means that you can use it in the car and elsewhere without too much trouble.

Secondly, while the enerloops are great, the low-self discharge batteries have lower capacity than the more traditional models. If you need more than around 2000mAh per AA, you are better served by the 'regular' NiMH chemistry cells. These come in capacities as high as 2700 mAh last time I looked. If you are charging and using immediately (camera flashes, or any heavy current draw items) the advantages of LSD are lost.

Whichever cells you go for, the Powerex chargers are fantastic. You can check the performance of the cells (vs rated) and keep them in 'pairs and quads' with matched capacities and you get much better service from your batteries. Also let's you find the cell that is dragging down the performance of the others and identify which ones you need to replace. Cannot recommend it enough.