Hi. I need to create private key for bitcoin that I can print out. I have learnt about https://www.blockchain.com/ and https://www.bitaddress.org. What would you recommend?

When creating a paper wallet, the burden of creating such a secure, isolated environment falls on the user. To mitigate the risk of the wallet being compromised from the start, you should use a live Linux from a CD, disconnect from the internet (preferably, you would use a machine which has never touched the internet before), and limit yourself to a “dumb” printer (with no access to the internet).