I would say Selenium standalone Server is good for several reasons:
It tests distribution over the remote machine, or multiple machines (nodes),
Selenium tests on different browsers with different versions,
Test that is not developed using the Java bindings (i.e. Python, C#, or Ruby) and would like to use HtmlUnit Driver
You should choose accordingly.
For more info visit https://intellipaat.com/blog/tutorial/selenium-tutorial/.
I am mentioning a video tutorial which I personally found very helpful. .