I was hesitant to buy a quick charger because I thought It might quickly reduce the battery life of my rechargeable AA's. Quick research shows it is partly true! However, don't let it stop you from buying one. After reading an article about battery myths, I found out that a smart fast charger only differs by a small amount and might even be better than a slow (and not so smart) one. Why? Because it is more likely that you'll forget that you are charging for 10 hours compared to, say, two hours and overcharging reduces the life of batteries.
There can be a confusion what a "quick" charger means, reading Eneloop FAQ, it is stated under Can I use a "Quick Charger" to charge an eneloop battery? that a Quick charger is NOT recommended. The charger should be two hours or more. But I already consider two hours a very quick charger (compared to 10 hours or more!). Apparently there are really quick chargers that can be bought these days (e.g. 15 minutes!). These chargers are not recommended, maybe only for emergency. I am happy with a two-hour quick battery charger from Eneloop. Happy charging ;)