To answer the original question, we offer 2 things beyond the competitors:
More flexibility: You can style elements, and you dont need to use the bootstrap containers (or bootstrap) if you dont want to. This is cool as we've been able to design all of easel inside of easel itself.
Collaboration: A very central part of the design process. You can share designs with your team, create clickable prototypes to test your ideas, and everyone invited can leave comments.
Our goal is to make easel awesome for all your web work in a professional team setting.