I like doing CRUD apps, beyond the trivial you run into a terrific amount of business logic and thats an opportunity to really have an impact, one of my proudest moments as a programmer was taking a process that was largely manual and took 3 staff 2 days and making it something the boss could do in half an hour on a Friday afternoon by redefining the underlying assumptions about how their business worked - it's amazing how many businesses do <involved complex manual process> because that's how we've always done <involved complex manual process>.

It's 2017, We've had desktop computers for 35 years and most of the people I know working in various industries still manage a huge chunk of their work in email and excel because it's hard for their management to understand the benefits of automation or why they'd make an investment in the longer term with good software, I know of one company thats in the FTSE250 that manages it's entire pallet and tray inventory by using excel spreadsheets on a shared drive and sending people from the office to sites to look whats there (they order 100K+ Trays at a time).