No comparison - Flash wins
and not just because we're on FlashKit - I have motivation beyond that.
When it comes down to it, there's two things that make me choose Flash over HTML. The first is the cross-browser problem. HTML and the unavoidable JAVAScript add-ons which add some additional dimentionality to the flat front can sometimes be seen on one yet not on another browser. For whatever reason, this is an unacceptably weak link which is solved by using the nonbrowser-specifc content of a Flash movie.
The other is a more esoteric point. I got into the whole website thing because I thought that as a self-styled design guy, I'd be able to put my ideas to good use. 30 live sites later (countless demos and other animated work too), all designed solely by yours truly, 90% in Flash, I've become bizarrely profficient at manipulating images and vectored graphics within the Flash environment, to the point where I sometimes use Flash to create even simple non-animated images. True, it can be a pain when they release new Flash versions, and some of the features are not always useful for my work, but that's neither here nor there - if you take the time to practice, Flash is easier and quicker at producing better product than simple HTML.
Cheers