Apple chargers are cleaner… a normal transformer will convert AC to DC then lower the voltage to 5DC and thats it, call it a day.

An apple transformer will convert AC to filtered High voltage DC then it will converted back to low voltage AC and converted to filtered low voltage DC … is a double step, thats why they are expensive; and their voltage is cleaner and consistent with no spikes… smooth voltage, since the secondary transformer tells the primary to regulate voltage… you always get smooth as butter good old filtered dc power.

With that said, get apple branded.. if not, then anker or Belkin or mophie are probably the next best thing.

But in reality any transformer will do.

Even decepticons