I want to use UnityScript as it sounds easier to learn, but I also want to make the best quality games and take the best route. As long as I can make large scale games like Skyrim I will go with UnityScript, but if C# will be the better path for stuff like that then I’m going with C#. I am leaving Boo out of the question since it is pretty much Python and I had a bad experience with stuff like that.
The difference between C# and JavaScript is not very huge. Generally, if you know UnityScript, it will not take you more than an hour to learn C#, and the other way around too.
C# is, as you most likely already know, faster. It is after all made for programming games and executables. JavaScript is a bit easier to understand, and for some reason, more people use it, which results in easier bug fixing, but it is a bit slower, and can be extremely confusing and limiting when getting into more complicated code.
My advice is to learn C#, and then just go with that. If you decide that you want to learn UnityScript later on, then that is most likely not going to be a problem, and you can easily learn it in a good hour.
All of the Unity classes and all .NET classes are available in both languages, so technically yes you can make the same game in either language. Not that it matters, since by the time you’re able to make something like Skyrim, it’s basically irrelevant since you’d be able to program in whatever language you need to anyway. In other words, you’re worrying about the wrong thing. Just learn Unity and how to program first.