The La Cross BC-9009 Battery Charger is good hardware. Nothing fancy, just charges AA and AAA batteries. But it's really good at charging. You can choose low current if you're not in a hurry and want to extend battery life or use high current for a quick charge. It has a mode where it discharges the battery first as well as a reconditioning mode that cycles the battery a few times. It's $46 on Amazon.
We use Eneloop NiMH batteries; they seem well rated. I'd love to use lithium batteries but there are few options for rechargeables; NiMH is more of a developed market.
I used to never bother with rechargeable batteries but we go through enough batteries in the airplane it's worth it. A hidden benefit is you can replace the batteries in your device whenever you feel like it; no need to risk running flat because you're trying to get every last milliamp out of your disposables.