What is most powerful programming language?
The lowest level is the most powerful, and consequently, also the most difficult to use. Higher-level languages make the task of programming easier, but you give up some of the power in exchange. There are things you can't do in higher-level languages. So, VB is very easy to use, but there's a whole buttload of stuff it can't do (try writing device drivers in VB, for example). It's not very powerful. C++ is MUCH more powerful than VB, but still there are a lot of things you aren't allowed to do. C is less restrictive than C++, therefore it is more powerful. Some things you can't do in C (and C++ for that matter) can be gotten around by linking libraries written in assembly, making your higher-level language almost as powerful as assembly. The least restrictive language (and therefore the most powerful AND most difficult to use) is assembly.
The one that you are familiar with. The goal is to make a computer do what you want where the only thing that really changes is what "functions" get bundled as part of the language. In the end, it all gets converted to machine language.
I don't think that there exists one language that everyone would agree is the most powerful. One could say that Java is the most powerful because over 3 billion devices worldwide use it. Or one could say that C is the most powerful because many languages are C-based, including C++ and Java. It's probably just a matter of opinion.