@jsalvador Learn all of them.
Scala is interesting for many applications and Clojure too.
It's a matter of taste but both are fantastic.
If you have time, you should learn Scheme first because it will enable the other two. Read the SICP and you'll learn a lot from what's going to appear in both Scala and Clojure when you reach them.
Scheme has not that many uses in the industry but it's a great source of knowledge about languages.