When comparing Ceylon vs Elixir, the Slant community recommends Elixir for most people. In the question“What is the best programming language to learn first?” Elixir is ranked 9th while Ceylon is ranked 42nd. The most important reason people chose Elixir is:
Leverages the existing Erlang BEAM VM
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Try it out in the browser
It has a Web IDE: http://try.ceylon-lang.org/ with impressive demos: http://try.ceylon-lang.org/?gist=bd41b47f325b6d32514a so you can try it without installing anything, and see the JS generation / interop in action.
Pro Strong static typing, null safe and flexible, almost dynamic type system
The compiler prevents you from using a potentially null variable, unless you check it is not null. Ie. it forces you to check a potentially null value before using it.
The type system is strict, but flexible, allowing union and intersection of types, covariant and contravariant types, reified types, etc.
Type inference and union types allows a dynamic programming style, close of JS spirit.
Pro Designed from the start to generate JavaScript
It brings type safety to JS, allowing to define interfaces to existing JS APIs, yet using the dynamic
keyword for flexible calls in the JS ecosystem.
Pro Excellent IDE support
Ceylon has reified generics, so it doesn't loose the type of collections at runtime. This makes autocompletion, debugging, etc. first-class. The Eclipse plugin makes it a full-fledged Ceylon IDE, and an IntelliJ IDEA plugin is in the works.
Pro Great tutorial
Gavin King, main author of the language, has a great, clear technical writing style, making understandable difficult concepts like variance or sound type system.
Pro Excellent documentation
The language specification is very complete and up to date; also, the language module is very well documented.
Pro Javascript interoperability
Ceylon has special language-level support for interoperation with dynamically typed languages like JavaScript, and its module system even interoperates with npm.
Pro Easy to learn even if you don't have prior programming experience
Ceylon is indeed fairly easy and readable. Of course those ones who know OOP and a bit of functional programming concepts will feel almost at home right from the start.
Pro Generate HTML
HTML generation is supported right in the SDK.
Pro Same code in backend and frontend
If you don't use platform-specific features, you can reuse the same code in your backend server (be it in Java or JavaScript) and in your client-side browser code, for example for storing data, validating input etc.
Pro Great for concurrency
Leverages the existing Erlang BEAM VM

Pro Great getting started tutorials
The tutorials are very clear and concise (even for a person not used to functional programming). Plus they are also very mobile friendly.
Pro Powerful metaprogramming
Write code that writes code with Elixir macros. Macros make metaprogramming possible and define the language itself.
Pro Full access to Erlang functions
You can call Erlang functions directly without any overhead: https://elixir-lang.org/getting-started/erlang-libraries.html
Pro Scalability
Elixir programming is ideal for applications that have many users or are actively growing their audience. Elixir can easily cope with much traffic without extra costs for additional servers.
More details can be found here.
Pro Great as a first functional programming language!

Pro Great documentation
Elixir's documentation is very good. It covers everything and always helps solving any problem you may have. It's also always available from the terminal.

Pro Syntax is similar to Ruby, making it familiar for people used to OOP
All of the benefits of Erlang; without as steep a learning curve of prolog based syntax. Elixir is heavily inspired by Ruby's syntax which many people love.

Pro Easy to download libraries
Comes with built in build tool called "mix". This will automatically download libraries and put them in the scope of the application when you add them to the "deps" function and run mix deps.get
Cons
Con Lack of physical or electronic books
We should hope Red Hat or anyone interested would take the time and write one. That would strengthen the maturity of the language, but Ceylon is rapidly developing which can make the author's efforts futile because his or hers work will become obsolete soon.
The second hindrance is, of course, popularity of the language which can't give much to the pockets of the author (however, Dart's unpopularity at start didn't prevent it to have a lot of printed material, but that's Google's child, we know).
Con Currently has large runtime
Ceylon 1.2 needs a language runtime of 1.55 MiB, and the Collection library adds another 370 KiB. That's a lot for the Web...
Now, this has to be put in perspective: if you use Ceylon to make a web application, these files will be loaded once, then cached by the browser (that's not casual browsing).
Moreover, most servers compress such resource, and the numbers become respectively 234 KiB and 54 KiB, which is more reasonable...
Con Deployment is still not as easy as it should be
Con Some design choices may seem strange
Some design choices could have been a little more appealing, for example: using "do...end" comes natural in Ruby for blocks but Elixir uses them for everything and it looks pretty weird:
Enum.map [1, 2, 3], fn(x) -> x * 2 end
or
receive do
{:hello, msg} -> msg
{:world, msg} -> "won't match"
end
