You are mixing Flash the plugin up with Flash the programming language.
With all of that said I also have to agree with Serapth that Flash is a platform that powers a proprietary programming language and can not be compared to an engine which is a set of API's, classes, methods and so on that simplify the game creation process. The answer I think I'm getting at here is pick a programming language that best reaches your target audience with fewest hassles and find an engine for said language if possible.
You can compile Flash programs to iOS native, Android Native, to Air and bundle it, etc... So you can make it so the end user have no dependencies, etc. you can even compile to HTML now.
Flash the plugin should die in a fire, but Flash the programming language isn't all that bad.