When comparing ClojureScript vs Web Components, the Slant community recommends ClojureScript for most people. In the question“What are the best solutions to "The JavaScript Problem"?” ClojureScript is ranked 4th while Web Components is ranked 29th. The most important reason people chose ClojureScript is:
Figwheel builds your ClojureScript code and hot loads it into the browser as you are coding! Every time you save your ClojureScript source file, the changes are sent to the browser so that you can see the effects of modifying your code in real time.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Live interactive programming with figwheel
Figwheel builds your ClojureScript code and hot loads it into the browser as you are coding! Every time you save your ClojureScript source file, the changes are sent to the browser so that you can see the effects of modifying your code in real time.
Pro Simple syntax
Lispness makes ClojureScript trivial to comprehend after an initial learning overhead.
Pro Easy to use existing JavaScript libraries
Clojure and ClojureScript are designed to be able to interact with their host. So the language by design makes it is easy to use existing JS libraries.
Pro Targets Google Closure-ready JavaScript for immense optimizations
Google's Closure Library converts regular JavaScript into a highly optimized form - including dead code analysis/elimination. It can even remove pieces of unused code from 3rd party libraries (eg, if you import jQuery but only use one function, Google Closure includes only that piece).
Pro Share application logic between browser and Clojure server
Clojure is also able to run web servers, so one can reap similar benefits to NodeJS in terms of sharing code between client and server.

Pro Can be used with React out of the box
Pro Excellent build tools
Both Leiningen and Boot are great build tools that manage code dependencies and deployment.
Pro Excellent tools for web development
ClojureScript has superb wrappers around React.js (see Reagent) that make building single-page apps a breeze. With figwheel, it's a web dev experience unlike any other -- hotloaded code, repl interaction, and instantly reflected changes make good development fun and fast. You can add things like Garden to make CSS-writing part of the same holistic experience and suddenly all development is a pleasant, smooth process.
Pro The Spec core library
From the creator of Clojure:
Spec is a new core library (Clojure 1.9 and Clojurescript) to support data and function specifications in Clojure.
Writing a spec should enable automatic: Validation, Error reporting, Destructuring, Instrumentation, Test-data generation and Generative test generation.

Pro Great for small—likely published—reusable libraries
Very extendable as a single-import base layer for visual controls and probably also something like a react-redux Provider.

Pro Works with any framework
Less recreation of the wheel and fewer wrappers.

Pro Fallback styling when not yet defined
Before a component's script defines the custom element—either as the page is loading or with JavaScript disabled—it can be temporarily styled via :not(:defined)
. This may prevent the need for SSR.

Pro Customizable templates via custom-recognized "slots"
slot="name"
and <slot name="name">
for customizing a component's HTML in specific areas of its shadow DOM. Also fallbacks when not defined.

Pro Stylable via custom-exposed "parts"
::part(name)
pseudo-element for styling elements within a component's shadow DOM.
Cons
Con Tooling is horrible
I've never seen worse tooling before. Writing tests and getting test coverage reports is near impossible. Tooling is brittle and clunky. Feels prehistoric.
Con Syntax may seem cryptic to people not used to Lisp
Lisp is sometimes called "syntax-less" and this is bewildering to those steeped in Algol-type syntax (Java, Javascript, C, etc). Being a dialect of Lisp, ClojureScript's syntax may seem cryptic and hard to understand for people not used to it. While Lisp has very little syntax compared to other languages and it's generally considered pretty terse, there's still an initial overhead in learning the language.

Con Not well-suited for application wiring
Having to serialize/deserialize data between components is not convenient. You'll probably still need a [light/simple] framework. Some things are still quite nice, such as using the light DOM -- think <option>
with <select>
and <datalist>
.

Con SSR is potentially more difficult
…if you need more than CSS' :not(:defined)
, that is.
Check out this video to see how the creator of SkateJS handled it: https://www.youtube.com/watch?v=yT-EsESAmgA
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