I use the Powerex MH-C9000 charger - lots of advantages once you learn what recharge rates work. For instance, if your AA Eneloop is 1900 milli-Amp, then you want to charge it at a rate of between 0.4 to 0.6 of 1900 (I use 1000 mA/hr rate) (500 mA/hr for AAA 800 mA batteries) - that means you can charge up to four batteries completely in about 2 hours. Or, you can condition battery to last longer by taking 40 hours. As I said, lots of choices.
Two linked advantages of rechargeables like Eneloop is that they "self-discharge" very slowly and therefore don't leak and ruin your electronics as easily as alkaline batteries. Related, since they don't discharge fast, you can leave them in your bedside ear-pro with pretty good assurance that they'll have power when you want them to.
I don't use Eneloops outside in my weather stations in the winter, however - that's a good place for Lithiums.
As a matter of interest, there are other rechargeable batteries than Eneloop, but when a big company bought them (Panasonic, IIRC) and tried to re-label them with the Panasonic brand they didn't sell. Panasonic had to reverse and label them Eneloop. I buy the regular strength 1900 mA AA and 800 mA AAA. Lots of recharge cycles in them.