Duster_360 has the right idea, I would go with a minimum power handling capacity of 200W. I'm also on board with getting the new 1000W iCharger once my 106B+ can't meet my needs (which hopefully won't be for awhile, but with the way battery tech is increasing who knows?) Can't really go wrong with any of the iCharger line-up. Look at it as an investment, like any piece of equipment in this hobby, and spend the money for something that will last.

P.S. I did buy one of the cheap 50W chargers as my first charger and I got rid of it after 2 weeks because it just couldn't keep up with my lipo packs. Don't make the same mistake.