I'm on the fence on this one, only because some of my favorite sites use Flash.
But I do know very well that Flash sucks, big time. I don't know how anyone can defend such a bloated pig of a resource killer. HTML5 should make Flash irrelevant.
In a world where the content providers are moving to consolidate their assets and formats for as much platform compatibility as possible, H.264 is the obvious winner over Flash. Adobe should just get it over with and throw in the towel.