I'm working on a big overhaul to my assistive technology app, SnapType. I'm using Balsamiq, the same program that I used 6 years ago, when I created my first app. It's far from perfect and I'm sure there are better/newer programs to use, but I've stuck with Balsamiq because:
1) I've already paid for it (No subscription fee. An amazing value considering the length of time I've used it).
2) I'm quick with the controls.
3) As a non-programmer, I can quickly get my point across when sharing the idea with programmers.
What Balsamiq doesn't do well (or at least, I haven't spent the time to learn):
4) High fidelity mockups
5) Interactive demos
6) Responsive design changes
For my curiosity, what programs do you use to create website/app mockups? What do you like most about those programs?