I started off with exporting Sketch designs into png and then animating in AE but looked around to do this with higher fidelity - tried InVision - but it seems like Framer.js is the best option for what I needed. However, it is far more of a commitment an steeper learning curve, since you'll need to use Coffeescript. Pixate is probably the quickest, easiest option for you - and has a great source of video tutorials to help you get started.