When comparing Mustache.js vs XSLT in-browser implementation, the Slant community recommends Mustache.js for most people. In the question“What are the best JavaScript templating engines?” Mustache.js is ranked 4th while XSLT in-browser implementation is ranked 31st. The most important reason people chose Mustache.js is:
Mustache provides you with a clean and easy to understand syntax. Having a syntax that is readable is always a huge plus, since this means easier maintenance and code readability in the future.
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Pros
Pro Clean syntax
Mustache provides you with a clean and easy to understand syntax. Having a syntax that is readable is always a huge plus, since this means easier maintenance and code readability in the future.
Pro Available in lots of languages
Available in a wide variety of languages including Ruby, JavaScript, Python, C++, Scala, Go, Julia, Swift and more. See the full list here.

Pro Lightweight
Mustache is easy to deliver. If you need more features down the road, you can switch to handlebars, which is a superset of Mustache.
Pro Logic-less
By design logic-less templates force you to separate concerns thus helping you avoid future problems with refactoring. It also allow templates to be used with multiple programming languages without changes.
Pro Server side support
Mustache.js has multi-language server side support, which essentially means you can use mustache based templates on languages other than javascript. (like if your server-side was built on Java you could still use Mustache.js)
Pro Popular
This would mean that you'll have a large community to help you out if you run into any problems.
Pro Can be compiled
Mustache templates can be compiled to JS files, so that they can be directly loaded.
Pro Permits pipelining
I.e. apply one template on top of another.
Pro AOP model
With ability to split feature implementation apart from main codebase, development became quite more manageable. Example: for data of particular type you could define own rendering or render refine rules; pipelining allows incrementally change UI by adding/removing elements depend of parameters, data values, previously rendered content.
Pro Native multithreaded implementation
Only template engine which utilizes multithreading.
Pro Native pre-compilation available
In some browsers(IE) XSLT during load is compiled into DLL. In others pre-loaded template allows to skip recurring parsing .
Pro Accept native data out of JS heap
XML when stored, saved outside of JS heap, capable to work with amount of data 100x larger of JSON.
Pro Native implementation
Supported in all browsers, starting from IE5.
Pro Server side rendering
XSLT is available as in browser as on server side via various libs including highly optimized for CPU.
Cons
Con Basic tasks are difficult
Mustache js's attempts at making some things simple makes them so easy that they're almost difficult. That is the case with some basic tasks like figuring out how to apply css to shade odd/even rows on your template based content.

Con Bested by Handlebars in many ways
Handlebars being an extension of Mustache bests it in both speed and power. It adds additional features to Mustache which make writing templates easier and faster.
Benchmarks have also shown that Precompiled Handlebars renders in about half the time of Mustache and the rewritten Handlebars (current version) is 5 to 7 times faster than Mustache.
Con Lack of SDLC for in-browser development
It will take time to collect complete gentleman set: debugging, modular development, documenting, unit tests, etc. Please share if know the book on subject.
Con Verbose syntax
Takes time to get used to.
Con AOP model
Is complex to comprehend, justifiable on complex projects.
