RE: LiPo chargers. What is the best?
A charger that charges through the power plug does not cause the pack to go out of balance, the pack does that to itself.
Through the power plug, the charger can only see the total voltage of the pack. For a 3 cell pack it will take it to 12.6V. It can't tell if the cells are even or not. If the high and low cell differ by only .01 volt then every charge one cell will be high and one cell will be low. Over many charges that gap will grow. Same happens on the discharge. One cell will finish lower than the others. Over time the gap grows. If it gets wide enough it can impact performance and eventually pack life. The more cells the more prone to imbalance packs can become.
A balancing charger can see the individual cells. It can either charge them individually, the way the Cell pro chargers do, or it can charge them, then balance as some of the others do. Both methods work.
Or, you can use you regular lipo charger with a separate balancer and do the balancing after the fact. That works too.
All three accomplish the same thing, just in different ways.