Next-Generation Responsive Web Design Tools

It's great that there are finally new options for web design software. None of these will ever take off if they don't give them to students for free. We don't have time to go down a rabbit hole by testing all these apps. I hope there's a clear winner in the bunch. From Brian Wood:

These responsive design tools are probably here to stay in some form or other. Ever since mobile devices came on the scene, we’ve been trying to configure our workflows to accommodate responsive designs. These tools could potentially bridge that divide when used either as a starting point for front-end design or simply for wireframing and prototyping.