TD; DR

There is no "best repository".

Discover the official repository

Each project is hosted in a repository. At most it can be mirrored in other repositories.

For example, JBoss projects have their own repository where you find all products in their latest versions, but after a while the repository is synchronized with maven's central. So it's a good idea to add the JBoss repository to your project if you want the latest updates.

To find the official repository for a library, you should always look in the documentation or on the official website.

Private repositories

It's important to remember that each company usually has its private / internal repository to store the artifacts of its products in development.

So it's always good to keep your settings.xml file up-to-date with company standards. Check with the people responsible for the pattern. Also, configure the respective additional repositories for each project that requires artifacts that are not in Central.

Determining and searching for dependencies

If you have questions about a dependency, you can search on sites like MVN Repository , which is nothing more than a Maven Central indexer .

Unfortunately, sometimes finding a specific dependency is not enough. Many projects require a set of dependencies that is not intuitive to discover. This is common in JEE projects.

In these cases, it is best to look for an example project instead of trying to guess all the dependencies needed to work with a technology, which may vary depending on the type of project.

For example, depending on the Application Server used in a web application, you may have to configure your pom differently as these servers provide different libraries.