Obviously, it depends on the app you're trying to make. But I recently worked with a founder who found a niche, used Gravity forms to collect data, Gravity view to display and export the data, (your basic CRUD in programming parlance) and this solved the basic needs of the problem.

I presented on this a couple years ago at a WordCamp, and am giving the updated version in a week at WordCamp Belfast. https://wordpress.tv/2017/06/05/corey-maass-rapid-web-app-de...