What are the main advantages of Vickers hardness testers?

Taiwan Nakazawa Co., Ltd. answers for you: The main advantage of the Vickers hardness tester is that the hardness value is basically independent of the test force. As long as the material is very uniform, the test force can be chosen arbitrarily, but the measured hardness value remains unchanged. This is equivalent to having a unified scale across a broad range of hardness.
The Rockwell hardness test can only use different test forces based on different hardness requirements. In the low to medium hardness range, for the same metal material with relatively uniform hardness, the hardness values obtained from Vickers and Brinell hardness tests are basically approximate. For example, when the hardness value is below 400, $HV \approx HB$. On the other hand, the test force of a Vickers hardness tester can be as small as only 10gf, making the indentation very small and particularly suitable for measuring relatively thin materials.