Use a Trezor and use a secret word option with it. In this way, even if they steal your Trezor or if they find your word seed, from where they can get your coins, they will have nothing.

Two problems still persist with this method. First, they take you hostage and make you give ghem your secret word. But this problem is unsolvable and exist with all methods.

Second problem, you get into car accident and you lose you memory. You are screwed since you forgot your secret word.