Far better to back up a seed phrase and the first couple of addresses, generated by a secure piece of airgapped wallet software.
Now that you mention it: Electrum should have a PDF-feature for that. If the user has to manually copy/paste the addresses, keys and QR-codes to be able to print one page, chances are they mess up.
So we need trusted open source software. The only reason websites are still in use for paper wallets, is because it's the most easiest way to create them.