IMO the safest way to keep bitcoins is multiple paper wallets stored in safe locations like multiple bank vaults, the possibility of your funds being compromised is minimal since even if a bank is robbed the possibility of your codes being used before you use another copy to load them and send them away is relatively small, Hardware wallets are very expensive IMO and have the same vulnerabilities as saving your BTC in a computer.
Hardware is pretty hard to beat as far as safe storage that you can really access. Paper wallet is a good option aswell if done right.
One thing I would do is not have a paperwallet with bitcoin all over it. I would photoshop it or edit it somehow and put something like 'Link to family vacation 2014".... something a thief would care less about.
Keep some in hot storage in case you need it. But by far make sure majority is in cold wallet or hardware wallet.
everything can happen and we just need to be cautious 
