Ranked in these QuestionsQuestion Ranking
Pro Server side rendering
Deku can render it's components and data server side, then it sends those components as HTML to the browser.
This ensures faster initial loading time and SEO friendliness out of the box, since it's indexed as any other static website by search engines.
Pro Easy to learn
Since Deku is very lightweight and has a rather small API, there's not much to learn. It's pretty easy to get started and build something with it.
Pro Can use JSX
Developers using Deku can choose to also use JSX if they want to. This is especially helpful for people who are moving from React to Deku.
Pro Good performance
Deku's diffing algorithm is considerably faster and performs better than most libraries. The dbmonster performance mini-app written in Deku renders roughly 16% faster than other libraries.
Pro Extremely simple to implement.
To get started is extremely simple. It has a low learning curve.
Pro Seems to be quite stable
Even the most complicated GUIs are bug-free most of the time.
Pro Great support from the webix team
The company behind webix is really quick in answering any questions you have on their forum or via email.
Pro Webix Jet
The webix Jet library adds all the required features for SPA development (routing, template loading, ...)
Pro A lot of widgets
Webix is one of the most extensive UI component libraries, second only to Sencha ExtJS. Not only considering the number of widgets, but also the API methods for manipulating these widgets.
Con No support for legacy browsers
Deku does not support legacy browsers, or relatively old browsers for that matter. They only support the latest versions of the major web browsers.
Con Not a lot of learning resources
Since it's a rather new library and has a small community, there are not many examples where you can learn from out there. There are also few guides and the documentation is not amazing and has some parts that should be covered better.
Con Not modular
The library is not modular (except for some additional more complex widgets). If you only need a few widgets, you still need to include the entire library.
Con Commercial license
It's not free for commercial applications.
Con Not very popular
Not really a reason to not recommend it. But it has still a small user base. It deserves a lot more attention.