Which service to use?

The answer may vary depending on your choice of Build service/tool in your pipeline and your use-case. Generally speaking; S3 is the most common place to store built artifacts and it has native integration with AWS DevOps services, i.e. for AWS CodeBuild & CodePipeline S3 is the only option. Also there are plugins for other popular build management services i.e. TeamCity...
If you use package managers such as npm, yarn, pip, twine, and mvn to publish packages developed within your organization AWS CodeArtifact is a better alternative as central organizational repository.