The ease of use, how well documented all aspects are! I have used other JS libraries but they were not as intuitive or straightforward in their approach compared with markOJS which was very clear when trying out this library for my project requirements. Try them both if you can- You will be surprised by what each one has to offer depending upon needs/requirements etc.. Nothing so far!! We needed an interactive web view (like WebView) where we could display some data from our server side API call without any page refresh required after initial load. I like how easy it was to get started with Marko, as well as how easy it is to learn. It's also very intuitive. There are no features that I dislike so far. This is an excellent tool for building rich UIs without writing tons of code. Marko allows me to create reusable components in minutes. The markup is easy to read and understand. You don't have to write any JavaScript or CSS. I'm able to quickly build custom controls that can be used across my entire application.