My experience has shown most tutorials are written in Javascript for Unity :\
Most documentation in their site is in both languages, although they default show "Javascript." Btw, it's not actually javascript, not even javascript-like, its closer to Flash's Action Script from all I hear and internally referred to as UnityScript.
It tends to be best to start with C# because it's better, a bit more industry standard, and you get documentation for the raw language and .net frameworks from Microsoft (you don't get that for "JavaScript".)
Also this "JavaScript" does a lot of shortcuts and allows for a lot of bad practices that should be avoided. I made my first game in that language and saw myself being forced to port everything to C# later as I attempted to incorporate certain functionality and increase performance.
It IS a shame most their sample projects are actually available only in "JavaScript", though...