Axure RP offer a layer based stacking for the designs components which makes it much easier to create interactions with different elements of the design. Also, what is great about Axure RP is that it publishes the prototype as a clickable web based HTML prototype which can be opened up in any browser.

Axure is quite powerful. I can build wireframes, flowcharts, import images for mockups and build prototypes (animations/transitions) in it.

I like how fast it is to do wireframes with Axure. They have Masters, Dynamic panels, etc that allows to have a very efficient workflow. It is also really easy to do complex prototypes. It is the only tool that I know of that allows to do conditions and pass variable to create very interactive prototypes.