I’ve been hearing a lot of Flash vs. Ajax arguments lately, and unfortunately, they almost always start off in the wrong way.
It’s very common to hear people argue about Flash websites or RIAs vs. Ajax websites or RIAs, but this is always the wrong way to approach building any website. Would you have an argument with an architect about whether to build a house out of wood vs concrete? Of course not, they would use each material to build the parts of the house that the respective material is best for. Sometimes you might want to build a shack or barn out of all wood, sometimes you might want to build an all brick house, but many times you’ll want to use the best material for each section of the house. Build the foundation out of concrete, the walls and roof out of wood.
Another example is Flickr. They started out using Flash to display all of the images, including the image notes and the other toolbar options along with each image. While this might have been a good choice as the site started out, it was soon replaced by a more efficient HTML version of the toolbar and notes system that works just as well as the Flash version. They did end up keeping one small bit of Flash so users can rotate images and see a preview before they save it.