Machine code is the most powerful! Not only that, but it's easy; you only need two of the keys on your keyboard! It's fast, it's compact, and you can do anything in it!
Damnit, now I'm back to sounding like a C++ programmer.
But seriously; each of those languages is Turing complete and, therefore, as powerful as anything else out there.
Einheri : In one of my brighter moments (in the bathroom) i took a roll of toilet paper and the black and white checker tokens i have and build myself a turing machine. I guess the point is... who needs computers and machine code ?
But seriously... isn't computer science the art of abstraction ?
And your hobo-computer would be able to perform any operation that C++, FORTRAN, or hatever could perform. Therefore it is just as powerful. The key point of my post was the part about choosing which makes your life easier; For exaple, you probably could write quake 4 using some tissue and a bunch of checker tokens, but it wouldn't be making your life any easier. Similarly, but to much less of an extreme, you could write a MMORPG back-end in C, but something like Java might make things an awful lot nicer for you.