I prefer Rechargeable AA and AAA batteries since they are cheap compared to replacing those bult-in or proprietary batteries for Cellphones, Digital Cameras, and other devices.
I been using Rechargeable AA batteries for my Xbox 360 controllers, and they work pretty well.
Same for me, but I find some of the proprietary batteries which are weirdly shaped for digital cameras are kind of expensive, so I tend to prefer AA Energizer "Rechargeables" for my Digicams since I can carry an extra pair of rechargeable batteries if I am taking pictures for many hours like 5 hours since I tend to take hundreds of photographs at a time, but I notice after a few hundred high resolution 10 Megapixel photos my camera runs out of batteries and I can't just put in a pair of Rechargeable AA since my Camera uses a proprietary battery shape which is rectangler.