I don't think there's really a straight yes or no answer to this question. I would say that the following guidelines should be used to pick an encoding format, in order of priority listed (highest to lowest):
1) Pick an encoding your tool chain supports. This is a lot easier than it used to be. Even in recent memory a lot of compilers and languages basically only supported ASCII, which more or less forced developers into coding in Western European languages. These days, many of the newer languages support other encodings, and almost all decent editors and IDEs support a tremendously long list of encodings. Still... there are just enough holdouts that you need to double check before you settle on an encoding.
2) Pick an encoding that supports as many of the alphabets you wish to use as possible. I place this as a secondary priority because frankly, if your tools don't support it it doesn't really matter whether you like the encoding better or not.
UTF-8 is an excellent choice in many circumstances of today's world. It's an ugly, inelegant format, but it solves a whole host of problems (namely dealing with legacy code) that break other encodings, and it seems to becoming more and more the de facto standard of character encodings. It supports every major alphabet, darn near every editor on the planet supports it now, and a whole host of languages/compilers support it, too. But as I mentioned above, there are just enough legacy holdouts that you need to double check your tool chain from end to end before you settle on it definitively.