When comparing Inferno vs Fit.UI - Object Oriented UI framework, the Slant community recommends Inferno for most people. In the question“What are the best open source JavaScript GUI/widget frameworks? ” Inferno is ranked 7th while Fit.UI - Object Oriented UI framework is ranked 14th. The most important reason people chose Inferno is:
Use it however you want in a framework of your own custom design. When things change in the industry, swap things out instead of being locked in by someone else's design.
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Pros

Pro Modular
Use it however you want in a framework of your own custom design. When things change in the industry, swap things out instead of being locked in by someone else's design.

Pro Pretty light-weight
Inferno weighs in at 9kb gzipped, which is light-weight.

Pro Fast performance
Inferno is one of the fastest UI libraries around and widely considered the fastest.
Pro React compatability
Using the Inferno compatibility package ("inferno-compat"), Inferno can support the vast majority of React codebases.
Pro Completely free and open source
Most UI frameworks seems to be really limited or cost money. Fit.UI is actually quite comprehensive and licensed under LGPL which means you can use it for any kind of project - commercial, personal, or open source.
Pro Full intellisense for JS and TypeScript in Visual Studio Code
You never have to look look up the names of functions - Visual Studio code just lists all the possible functions available on a given Fit.UI object.
Pro NPM package available
It can easily be installed through npm: npm install fit-ui
.
Pro Enhances productivity
You can create a fairly complex app in little time from scratch using Fit.UI.
Cons
Con Some React components may not work with Inferno
Inferno and React have different public and private APIs. If 3rd party components use a private API then it's almost certainly going to break when you use it with Inferno.
Once React Fiber is implemented, even libraries that are currently working will break and will not be supported by Inferno.

Con Not very popular
Which can hinder one's opinion of its future, but the future of all "frameworks" is to break things into smaller pieces, so inferno very well might get used by the big names in the future.
Con Not as much third-party resources available
Since it's not as popular as other libraries there are not as many third-party resources like plugins or tutorials available.
