I have been through so many of these tools - creating a really good wireframing/prototyping solution is obviously not a simple task.. Been looking for an alter

I have been through so many of these tools - creating a really good wireframing/prototyping solution is obviously not a simple task.. Been looking for an alternative to Omnigraffle, mostly due to its lack in the prototyping department. Really loved the way Mockingbird handled this but the nativeness and user community of Omnigraffle still makes it hard to beat..