That's all they are, the most popular ones, exactly the same as ICObench as they are the most popular ICO tracking/scoring site too. Being audited by Certik means squat, but is often used by scammy shitcoins as  pitch, to appear more legit. And exactly the same thing as ICOs were using ICOBench back in 2017, bragging about the score on their websites.

I have a friend that is working on a project, and they paid shit load of money to Certik to find possible bugs in their code. Recently, they stumbled upon a major bug (luckily before hackers) in their smart contract and completely rekt them, which Certik failed to identify. So yeah, you can pretty much ignore "audited by Certik" thing when you are DYOR on some altcoin.