Depends on your budget.
<$50: Turnigy Accucel-6
<$100: iCharger 106B+
Unlimited: FMA PowerLab 8
This is one of the many threads regarding balance charging using a hobby charger:
http://www.candlepowerforums.com/vb...Tech-Tricks-Homemade-Balance-Charging-Cradles
Unsure if this is THE BEST charger but I have just been given a nitecore charger for Christmas by my girlfriend
http://www.flashaholics.co.uk/batteries/nitecore-intellicharge-i2.html
I have just charged up two cr123s and my first impression is it seems like a very well made device!