When we test VPNs, we use the Ookla speed test tool. (Note that Ookla is owned by PCMag's publisher, Ziff Davis.) This test provides metrics for latency, download speeds, and upload speeds. Any one of these can be an important measurement depending on your needs, but we tend to view the download speed as the most important. After all, we live in an age of digital consumption.
That attitude to the safety and privacy of personal data creates an enormous online security risk. Public Wi-Fi networks, which are ubiquitous and convenient, are unfortunately also highly convenient for attackers looking to compromise your personal information. How do you know, for example, that "starbucks_wifi_real" is actually the Wi-Fi network for the coffee shop? Anyone could have created that network, and they may have done so in order to lure victims into disclosing personal information over it. In fact, a popular security researcher prank is to create a network with the same name as a free, popular service and see how many devices will automatically connect because it appears safe.