Proto.io can be more complicated than some of those tools because it gives us a lot of features in the same product. Some of those tools are better for wireframing. Still, for prototyping, my choice is Proto.io because its prototyping workflow, even if it can be a little …
In the end, we decided not to continue using Proto.io and instead use tools we were already using.
For just presenting workflows to stakeholders, InVision worked almost as well (not as robust in interactions, but when you want to focus on the steps, that's better anyway).
Proto.io is definitely the premier mockup and wireframe application. Lucidchart shares some of the capability but can be a bit clunky. Proto.io is interactive and smooth and helps you to see exactly how your UI will look and behave before the development stage. Additionally, …
Proto.io is web-based for one, which is a plus - Adobe XD is a desktop application. Adobe XD has some great features, especially for a free product, but from what I experienced Proto.io had way more tools and customization for creating interactive prototypes. Adobe XD is good …