I have taught intro programming classes in VB, C, C++, Java, C# and Pascal.
VB is clumsy and it is awkward to say some things. Besides, the .Net version looks too much like C#.
C# and Java are interchangable in this sense. Java wins by portability. But you have to jump a bit into the deep end. I have to explain OO programming almost before discussing variables.
Pascal has too many types.
C and C++ are great languages but it's a bit like teaching intro to wood carving using chainsaws.
I have only looked a little at Python but have a hard time getting by the use of whitespace as syntax.
So I suggest JavaScript (or ECMAScript).
Everybody has the development toolset already on their computer. The console in FireFox is handy for error discovery. Working in a web page is more fun than most IDEs. The basic syntax is the same as C, C++, Java and C# so the skills carry over. Pretty weak on OO programming, though.
Good discussion.