It seems that there pops up a new prototyping tool every day. And for me there is not the ONE AND ONLY prototyping tool. Instead I use whatever I need for the specific situation.
a) Basic Prototypes (quick, easy, WOW!)
InVision is my number one app for basic protos! For me the value of InVision is creating wow-looking prototypes for different devices in very short time. Although it has other features beside prototyping I don’t really use them. Within a few minutes you can create a prototype that shows pretty much how the experience with your piece of software could look and feel. I use InVision for discussions with team members, stakeholders and for user testings. The downside is that the interactions, animations and transitions you can use are rather basic.
b) Totally realistic prototypes for the web (“When can you bring that live?”)
Axure RP is the grandmother of prototyping tools. I first used it back in 2007. There was a time when you did not come across Axure if you wanted to build a digital prototype. With Axure you can build nearly everything that runs in a browser. You can play with variables, dynamic content, user input etc. to bring your prototype to live. I use it for testing complex scenarios in a thinking-aloud-test with users for example. The price for this flexibility is that Axure is complex, it has a steep learning curve and a relatively long development time. So if you plan to create a hi-fi prototype in Axure, consider working in Axure right from the beginning. Otherwise you need to re-build all your previously created screens for the prototype.
c) Realistic Interactions or sequences
ProtoPie is the tool I use for building hi-fi interactions. While InVision is good for showing whole user flows. ProtoPie is meant for focusing on single detailed interactions or short sequences. It’s built on the concept of object, trigger and response. So an interaction (i.e. drag) on an UI-Element (i.e. button) leads to a response (i.e. animation) or a chain reaction of responses. And you absolutely need no coding skills. You can watch your results directly on your device or inside a preview window.