Hello Khaleb,
There are many impressive and innovative use cases, we can see from mendix community and customer success stories.
I worked on multiple Factory digitization appl, Customer, Supplier creation App, workflow-based app. Chatbot app which was bit different and challenging.
For me personally, I love working on projects that have a visible real world impact. One of the projects I did via Conclusion was at a Dutch railway company, NS. While the technology wasn't groundbreaking, the app made a real impact in how people worked, and seeing it translated to better travel experiences for travelers was very cool. We even ended up winning a Mendix award with the app!