The company rankings, seem to correlate by how much they spend on ads and recruiting campaigns.
But what's strange, to me at least, is that FAANG companies also dominate those list - despite the fact that they only have very small satellite offices here in my country (in Scandinavia), where they work on quite niche products / problems.
I always found it a bit curious, when talking to highly motivated and talented young people in tech, that basically dream about joining companies like Microsoft, knowing fully well that they'll be working on some Office 365 feature - probably fixing bugs.
Microsoft, on their side, can pick and choose among talent - because they'll get run down with applicants either way. They could hire good students with Master's Degrees, make them janitors, and still it wouldn't even dent their reputation - because kids will blindly follow lists as mentioned above, and the dream of a prestigious employer on their CV.