I prefer one that's at least 40 watts. I ordered this one Aukey Amzdeal Multi Port USB Charger Charging Station USB Wall Charger (40W 5V/8A 5 Ports) 16.99

http://www.amazon.com/gp/product/B00K4XC8EO/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1