MockFlow is a great tool for low-fidelity wireframing for quick validation & contextualization of UX & UI hypotheses. It is not a substitute for full-fledged designing tools such as Figma or Adobe XD.
Proto.io is the perfect solution for UX/UI designers that need to create and share interactive prototypes. Proto excels at the interactive part. There are so many different ways to make elements change or interact, whether you're viewing the prototype on a computer (mouse clicks) or on a phone (screen touches). We could build and prototype our entire mobile app on here if we wanted to because Proto.io has the customization that we need to make the app look and feel like ours. If you're looking for a software to create wireframes and static mockups, Proto.io is probably overkill for you.
Figma is a high-fidelity designing tool and provides too many features which would be overkill if we are looking for basic prototyping. Also, if you are not a designer and just want to create basic wires or prototypes as a Business Analyst or Product Manager, MockFlow would suffice your needs. But if you are focusing on pixel-perfect designs then I would suggest going for Figma. The ease of usability with MockFlow is very convenient as there would be a steep learning curve for Figma. Balsamiq is very similar to MockFlow but the wires created in it look a bit sketchy & clumsy.
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, it's library of native components is robust.
