I did some vendor analysis with Backstage, Configure8, Mia Platform, Humanitec and then Port for our Platform Engineering team that wanted to develop an IDP, and Port was the best out of the pack in terms of features (catalog, actions, scorecards and data model), but also the UI/UX part. It super easy to understand and get started with.
Now, Port is quite new, and they may still lack small things, but what surprised me a lot after we started using it, is how fast the team behind Port implements new features and reacts to the customers feedback. I can only recommend giving it a try, it's a solid Backstage alternative that requires a fraction of effort to set up