For best security I recommend using a hardware wallet like a Ledger or a Trezor. Also, OpenDime is a nice wallet for cold storage and off-blockchain transactions. Always stay away from brain-wallets, those get hacked all the time.
Basically the bottom-line when it comes to securing bitcoins is entropy, entropy, entropy. That was the LBC Project's biggest weakness, they could only focus on extremely low entropy keys. And none of the wallet programs out there ever use low entropy keys with bitcoin.