The most suitable cryptocurrency faucets are the one that have been functioning for several years, pay frequently, and are using known coins. There are so many crypto faucet for the popular coins like Bitcoin, Litecoin, and Dogecoin. They tend to have easy tasks and a trusted payout system. The other good feature of reliable faucets is that it does not demand too much of your personal data which makes it safer in the long run.
Some of the best faucets I've ever seen are the ones that have been in existence for a long time, for example, FreeBitco.in. They have got a very good reputation for consistent payouts.
From my perspective, faucets dealing mainly with popular coins like the m Dogecoin or Litecoin, are the most secure. I tend not to consider faucets that push for uncommon tokens because, in my experience, those usually fade away.