This has been a point of contention for me, ever since I have had a desire to learn a “language” other than shell scripting. Which language would be most practical, valuable, powerful, reach the most receptive audience, designed with the ideals you share, what pays the bills, etc. Some, or all, of these aspects can conflict at any given point.
As for being practical or powerful, these measurements are based on your use of the language, which vary more than there are languages, so it is a continually refining target. As I continue to learn more languages, and deepen my knowledge of others, it is evident that no one language can be the end-all. Learning their benefits and drawbacks is a large part of efficient implementation.
As for valuable, this can be in a business sense, or marketability since. For me, this is the first real point of indecision. Fortunately AND unfortunately, this measurement has a callback to another measurement, “What are the ideals and motives of the language’s design?”. Business sense can be a fuzzy option sometimes. If you are a business unit that is exclusively a Java shop, it does not mean that all glue and helpers must also be java. Inversely, just because Perl is flexible and powerful, does not mean it needs to be built into a megalithic solution. The marketability of a language though, can relate more to the individual developer.
The evolution of all the available languages comes due to varying factors and motivation, and that motivation assists greatly in the type of community and reputation that a language accrues. These are the ideals that a language is evolved with. This is the perception that can be reflected back on a developer. Like how PHP was formed by a loose group of code hackers, perl was an overly flexible parsing and report language, ruby was started by a single humble person seeking to please others. Thus is the seed that grows the community. As soon as you state what language you write in, the other person immediately conjures stereotypes to cast over you. Regardless of good or bad, it is another expression of the eight mundane concerns. If it is blame or disapproval that you seek to avoid, then you find yourself not associating with a broader audience. And seeking praise and approval, you turn in towards like minded folks to reaffirm your expressed position. This may work out just fine for many, but it does put you at a great chance of clinging to an us-and-them mentality, which can be poisonous for you and the community at large. I’m not going to expand on that greatly, you can find more insight on that, starting by reading on ingroups and outgroups
And for many, they may not be an advocate of the language they know best, but it is what has been taught abd/or what they are paid to write in. That is okay, because you can learn other languages, despite the stereotypes others cast on you from what you’ve written in. There are soon likely to be a multitude of .Net folks, regardless whether loyalist or indifferent, that need to branch out to new languages. Thankfully for the open source communities at large, these folks have fodder to learn from, and become involved with to broaden their own experience.
While I have languages that I am more comfortable with, than others, ultimately I am an advocate for being a language generalist. Determining the best tool for the job requires having a broad idea of the pros/cons of many options. Forcing a project into the box you are most familiar with, is not always the most efficient or effective approach.