Use Electrum to make your cold wallet, which are those 12 words written by hand on paper. That's the best in my opinion.
For smaller amounts, you could use one of those gadgets, or a secure computer/mobile. Do not think of storing flash memory somewhere thinking that works, flash memory tends to lose its data over time when stored unplugged, so don't.
I keep telling people those hardware wallets are a really bad choice for cold storage, or an usb thumbdrive; just don't. If you are scared of the 12 words, be creative hiding them, could be a book or something. And remember to always have two physical copies in separate secure places.
Of course you could use core, if you live in a nice place with unlimited and fast internet, downloading the whole blockchain shouldn't be a problem. Too bad there are still places in this world like my country with garbage metered, capped, slow and unreliable links.
No matter which wallet you use, the main thing is to keep the private key secure. People only focus on the best wallets but does not care about the private key security as much as they should. For example if you have a hardware wallet but you write its private key / password on an openly accessible place, anyone can use that key to unlock your wallet.
