Before you condemn this as subjective, consider that there are differences between different frameworks. Writing something with PHP, I assume, is probably a lot less verbose and thus time consuming and expensive than writing it in binary. While the differences may not be as pronounced between the title options, I think there probably are significant differences which can result in, for example, a DoodleJump-type app taking more or less time to code in each.
Although there are other factors involved in choosing a framework, I'm just asking which one requires the least amount of coding and thus time and expense for equally skilled developers to accomplish the same thing (conjuring DoodleJump physics, a basic TicTacToe game, creating a UI, whatever). I'd appreciate links to sources if you have them, as well as direct experience comparing the verbosity of one or more in accomplishing the same task.
I'd most like to get an idea of how Flash and HTML5 compare to Corona (in terms of development time), but I'm also curious about the others.