I also use Duracell. However, it depends on which model scanner you have, how you use it, how much activity you monitor, how well they're charged, etc.
I use a 4-pack AA Duracell wall charger, which takes about 6 hrs to fully charge 4 batteries. If I just need to recharge the batteries (but they're not all the way dead) then I just leave the scanner plugged into a 9V cord overnight. I own a RS pro-106 and pro-164. With the 106, I can set a limited charge time(the scanner stops charging when the timer is up) so the batteries don't over-charge.
With a GRE PSR-100 I use at work (on full volume most of the time) I can use the scanner for up to 4 days without having to recharge the batteries! (8 hour shift days) And the radio traffic I monitor is pretty close to 20-80. 20% of the time receiving, 80% of the time on standby (scanning).
You could always use Energizer, I hear those work well. There you go...