py.test is very similar to nose since no boilerplate code is needed to aggregate the tests in it. It also has a good plugin system, and there are a great number of extensions available on PyPI.
py.test focuses on making the tests run fast, and is truly superior compared to the other tools in this area. The other notable feature is the original approach to fixtures that really helps in managing a reusable library of fixtures. Some people may argue that there is too much magic involved, but it really streamlines the development of test suites. This single advantage of py.test makes it my tool of choice, so I really recommend it.
In the next section, you will learn how to measure how much of your code is actually covered by tests.