Today, the more secure wallet are hardware wallets like Trezor and Nano S. They both quite popular and Cryptocurrency millionaires are currently using this hardware wallets because typically, crypto keys are saved in those device only and there would be no digital keys will be saved in any computer or cloud storage in order no one could see it or if someone hacked your computer, your phone or your cloud account, they will not get your digital keys or in any form that they could access your wallets and assets.