The problem with the first three is that they are no longer supported by the community.
If I had to choose, I would go with Steven Feuerstein utPLSQL. His approach is always good.
Pluto - Object Oriented PL / SQL makes it difficult to use. The guy who wrote this is pretty smart, but somehow the community was not interested and the project died.
Bottom line: using files to create test cases makes support and sharing difficult.
Oracle SQL Developer is the best you can get for free. Easy to use interface plus the most important thing: repository. You can share your work with others and with other projects. Simple configuration. Test cases can be created on the fly.
There is one more thing. The guys in the Oak table described testing the Oracle SQL Developer module in Expert PL / SQL Practices. Even if it is sponsored, they will not describe it if it were an absolute disaster.
My personal opinion.