The ease of development leads me to say python or ruby, because they are simple and abstract.
There are bindings to libraries like libSDL from these languages, which I would recommend using (SDL has been used commercially,) and it will severely cut down the amount of time you need to spend on unimportant details (like setting up a window etc.)
C++ is probably worth knowing if you're die-hard set on writing games I guess, but it is a very complicated language compared to almost any other and takes much time to master. It has a much better type system than C too, which, in comparison, is very very welcome.
I would recommend if you go this C++ route to use something like SDL and boost, because they will save you a lot of time doing stuff you really don't need to/shouldn't re-implement (we use boost at work - some parts of it are godawful horrific, others are incredibly useful.)
Hope it helps.