Now, I don't know about you, my readers, but I happen to know quite a few programming languages. I've spent many years learning them. Why? Because I've found that no language is perfect, no language is better than any of the others. Each has its domain of applicability.

So, it is quite consternating to see threads on these boards asking, essentially, "Language X vs Language Y". What on earth would make someone think that a particular language was "the best," or even "better." To me, and most professionals, this makes no sense. You use which ever language you are told to use, or whichever one you are most comfortable solving the problem in, if given a choice. More importantly, why would you think that you can get away with learning just a single language? You do realize that you are going to end up having to probably produce a scripting core for your game, which means at least one "scripting language." Heck, if you want to store your formats in an easily readable/testable format, then you will be using XML, which is another form of a language. Yes, yes, I know some people don't consider XML a language, but it has a syntax and a structure to it, hence it's a language.

So, here's some things you can think about:

Generics:
Ah yes, the great cornerstone of so many arguments. First of all, to clarify something: C++ Templates != Generics. Now, to get to the core of this: C# Generics vs Java Generics. On the surface, the two appear to be mostly identical. You define a type, passing it another type, and now it's methods take and return that type parameter instead of generic objects. There is a difference however. In C#, the generics are true generics. They are determined at runtime, and when the IL is generated, you get a type specialized for the input type. In Java, however, generics are just implicit casts. Thus Java generics give no inherit performance nor type safety1 bonuses. They just make your code prettier to look at. This is, in fact, one of my big disappointments with Java.

Templates:
Ah yes, the great cornerstone of C++, the gloriously hacked templates. There are so many dirty things one can do with templates that it's not even funny. That combined with the fact that most people don't really understand them (sure, you can use them, but do you understand why you need typename sometimes and why you don't other times?). Combine that with the fact that no compiler properly supports them (excepting one, and that one has other issues), and you have a royal mess of code that requires both preprocessor statements, template hacks, and generally bad coding habits just to get something to compile and build across two compilers.

Cross-Platform:
Heh, this seems to be the one big cornerstone of the Java world. To bad it's not true. I have yet to see any sufficiently complex Java application that didn't have hacks in it to get around operating system deficiencies. Even C# has these problems, and hence isn't cross-platform. For the most part, it's an issue of libraries. But, assuming you avoid such libraries (which can be very very difficult) you can presumably write applications which are "cross-platform", good luck though.

Standard Library:
Ever noticed how people will extol the virtues of the Java standard library, but yet will refuse to use the C++ standard library? Sounds kind of hypocritical, don't you think? Now, the library that comes with C++ is woefully small. But that still doesn't mean you shouldn't use it. But this is one of the advantages that C# and Java have over C++. Their standard libraries are huge. With .Net 2.0 coming out soon, the .Net Framework will nearly triple in size.

So what language would you use?
I like C#. I use C#. I love C#. I hate Java. I don't mind C++, but I'm not in love with it anymore. I will use which ever language provides the functionality I require. When a solution is better solved through the use of O'Caml, then that's what I will use. If on the other hand it would be better done in COBOL, then you can bet that that's what I will use.

Why should I learn multiple languages?
Because, to be frank, you are not a very desirable employee if you don't. In this industry, knowledge and the ability to learn and adapt to changing situations is much more valuable than knowing C++, or whatever this weeks favorite language is.

I should note, however, that esoteric languages do not count. No one really gives a damn if you know brainf*ck, whitespace, ook#, or YASOOL.

1The problem here is that since you can convert a List to an Object and then to the actual container type, you can completely sidestep the "type safety" afforded by the compiler. This is not possible with C# generics, as the container actually only holds T's, and not object's that are cast to a T.