Best device for battery life and storage capacity?

[jaiswalkhan]

I'm trying to find a new DAP for my spouse as a gift. Rockbox seems to fit all of his requirements for firmware features. I'm just not sure which supported device has the best battery life and storage. His last player (Cowon iAudio 7) lasted 100+ hours before needing a charge. Obviously he doesn't need something that lasts that long but it would be nice if he can listen to tracks while at work for a few days before needing to recharge the device. Thanks in advance for your help!