For what you are charging, 10 amps is plenty. Even if your charger is capable of putting out say 300 watts, if you never charge anything that high you will not need a 300 watt supply. So unless you intend to charge 3 or 4s lipos at 10 amps or more, a 10 amp supply will be enough. The nice thing about higher output supplies is that you can run multiple chargers off of just one supply.

The tiny little supply I use for charging all my nitro related equipment is only 8 amps.