We don't really have to debate on which of which offline wallets or cold wallets are best. If you are trying to compare some like electrum, coinomi, multibit, blockchain, etc... Mostly they are the same​ kind, same software that holds your private key and let you manage your coins. You can transfer your address on some of those stated walllets above. And to be honest, no matter what software you use if you are so careless as hell you might lost all your coins. So talking about offline wallets, they are just the same. Just make sure that you are downloading your software only in its official site. Nonetheless the security of the funds always depends on the user.

And talking about online wallets, just don't trust them when it comes to hoarding coins. Third party wallets will always be third party, and you will never know when will they shut down. Use them only for trading purposes and not for holding some.