Which multi cryptocurrency wallet is safe for long term holding that either stores private keys locally or gives users exclusive access to their private keys?

I am currently holding around 80 different cryptocurrencies in small amounts. I want to hold these coins for long term. Need a safe wallet where I will be able to store all my coins. As I have heard that servers where users' private keys are kept by wallets can be hacked, I want to hold my coins in a wallet which stores private keys locally or gives exclusive access of private key to the user (the one which doesn't store private key anywhere). I am not willing to spend money on hardware wallets. I am planning to store these coins on a desktop or a mobile wallet (or a wallet like metamask & myetherwallet). Planning to buy a new desktop or mobile which I will use only for the purpose of storing cryptos & will keep the device disconnected from internet until I want to sell my coins.