I would personally recommend an Offline wallet
Can we really use an offline wallet? If that idea is safer than online wallet, I think I will use that in the future because if we talk online wallet as of now specially connected to the internet network; vulnerability of being attacked by hacker is really possible to happen. I had no ideas of any offline wallets since my start of bitcoin transaction, online wallet is the wallet I used for a long period of time.
Well if you have substantial amount of Btc and still use online wallet, I would recommend to switch to some offline as soon as possible, Electrum would be great to begin with. While online wallets are still secure enough but since being connected to Internet it's easier to hack them, and then you also need to trust the wallet providing website if it doesn't let you control your private keys like coinbase or xapo.