They both kind of suck.<p>It's unfortunate that one of the best products for this category, Axure, is Windows only. It's incredibly unfortunate.<p>At massify, we've gone through 4 or 5 of these tools and because Axure is so good, we put up with running it in Parallels or VMWare Fusion. We're always keeping an eye out, but have yet to find anything better.<p>Here's our beef with Balsamiq:<p>* SLOW. PAINFULLY SLOW.
* Can't model interaction
* Can't model state
* Can't model multiple pages and link between them<p>Fundamentals really. I guess if you're designing a dialog, fine, but if you want a clickable prototype, forget it.