If you're referring to plug adapters, I prefer the block versus the whole kit. My REI adapter has seen years of abuse across the world and works great. Plus nice to have a USB plug on it in addition to the normal adapter. And if it ever fails, you could take it back to REI. However, I've put mine through so much I would just buy another one.

http://www.rei.com/product/837263/rei-usb-multi-nation-travel-adaptor-plug