If you problem is just generating a paper wallet, then you shouldn't use a random online generator.
You can use any well-known client like Bitcoin Core, Electrum, Armory, etc.  to create the address and private key.
You can use them to create a key pair on an Air-Gap Machine; ofcourse, the steps differ per client.

When it comes with trust, those mentioned wallets are "open-source", means that their source code is open for the public to check if there are malicious codes in it.
If you can't review it yourself, you can ask the users of those wallets if there's something wrong with their wallets
or ask someone who's an expert on the programming language of the wallet's source code.

For hardware wallets, most are closed-source because if they aren't, then it will be easier to find a vulnerability to hack their firmware/hardware.
People are trusting them (the famous ones) because it "stand the test of time".

BTW, this topic has been derailed too far.