Is xUnit better than NUnit?
The greatest distinction between xUnit and the other two test frameworks (NUnit and MSTest) in terms of NUnit vs. XUnit vs. MSTest is that xUnit is significantly more extendable than NUnit and MSTest. Instead of using the [Test] element, the [Fact] attribute is used.
In NUnit and MSTest, the class that contains the tests is under the [TestClass] attribute. This was not a very robust approach hence [TestClass] attribute was also removed in xUnit. Instead, intelligence is built in the xUnit framework so that it can locate the test methods, irrespective of the location of the tests.
Lean here for the Complete list of difference bewteen these 3 Unit Tets frameworks