Best battery powered looping pedal?

[Christopher Darrow <thedarrow@gmail.com>]

Hi. I'm wondering if anyone has a particular opinion on the best battery 
powered looping pedal. 

-  Currently available used.
-  New (if different) 

I know I could rig power via alternative sources but for this possible rig 
I'm looking for small and simple. (But of course responsive and at least a 
little flexible like a real live looper.)

Thanks for any thoughts.