The safest way to keep Coins is actually keeping them off the internet (Cold Storage ) to prevent them from getting hacked.I would recommend the Legner Nano S as it supports many alt-coins and allow you to keep the private keys to yourselves. As Legner Nano S are unhackable, the only risk of losing your coin is losing the Token itself . Even if you lose Legner Nano S itself ,using a seed phrase you will recover the funds still on another Legner Nano S.