The primary reason I chose the Ledger Nano S is because it is easy to use and is trusted by the community. All of your private keys are stored on the Nano S, and the Nano S is protected by encryption. When sending any transactions using the Nano S, they must be confirmed physically on the device, which provides extra protection. If you lose your Nano S, it isnt a big deal as you can simply recover your wallet by using the Seed key. Furthermore, to use the Nano S all you require are google chrome extentions which are easy to download and easy to use. I recommend the Ledger Nano S, I havent had any problems so far!