I use Principle mostly for quick demos when I try to communicate interaction ideas with my teammates. Principle is very good for this if you're not trying to create something too fancy but really want to share your ideas. Word to the makers: Keep the good work!
Kite Compositor is my new go-to prototyping tool. As a long time iOS developer, most of my prototyping was just done in Xcode because I had complete access to Core Animation. Kite, unlike other tools, is built on top of Core Animation and exposes all (or most) of its features directly. As a result, the animations it builds are almost guaranteed to look exactly the same on device.
Beyond that, it's just a well-designed app. As with most professional applications, the UI takes a bit of poking around at first to figure out how to do everything, but after just a day of playing with it, I became familiar with most of its capabilities.
Amazing tool for UI and learning Core Animation.
- I'm constantly impressed with the team at Atomic. I'm able to scale the fidelity of my prototypes really easily from low to high. Their recent additions like components, data, and team collaboration tools make it really powerful. You can see a more in-depth review in my Medium articles on "The New Generation of Prototyping Tools" Part 1 and Part 2.