I truly believe electrum is the best there is out there. It has so many feature including multisig wallet, 2fa wallet , standard wallet and cold wallet.

The OS is irrelevant as long as there is a version of electrum for it. For instance there is no electrum version to iphone but there is one for macos. I use an android for my offline wallet. This phone has never reached the internet since I installed electrum. And prior to install the app I did a factory reset. 

 true. having an old smart phone with electrum on it would be the best hardware wallet you can have. 

an old laptop would work too 😉 haha. airgapped laptop with electrum on it. I wouldnt think its uncommon amongst OG bitcoiners...