Truth is, if you’re starting to work with JS-based build systems, there is a high chance that you’d pick Gulp right away. The prospects for it just seem a little rosier, plus, it has been adopted by a large portion of projects. Yet, if you are still using Grunt and feel comfortable using it, there is nothing to be worried about — the community is still there, bigger than Gulp, and keeps growing. Grunt has almost a couple of years of advantage, and I am sure that large project maintainers will try to stick to it for as long as possible. Another advantage of using Grunt is if all you need is that little built-in set of simple tasks. In that case, you’d feel right at home with it, and Gulp, despite all of its flexibility, will make you spend more time in theory than you need. As with everything else project related, you should choose based on the circumstances.
UnderStrap combines the Underscores starter theme (by Automattic) and the mobil-first, responsive grid framework Bootstrap 4 (by Twitter) into a perfect open source foundation for your next WordPress theme project.