Why Gulp and not Grunt?
When I started out with task runners it was way back when Grunt first hit the scene and Gulp wasn't even a thing yet. Grunt has changed quite a bit since then and other tools like Yeoman have arrived on the scene as well as Gulp.
When I tried Grunt back then it was lost on me. I liked the idea of not having to refresh my browser and only having to run one command to do lots and lots of different things, but because I didn't understand how you did any of this before Grunt. I felt like the setup of Grunt, the Grunt CLI, and then all those brackets, were overly complex.
That was entirely because I had no experience with NodeJS before trying Grunt. When something went wrong (and things went wrong for me often) I had no concept of why it might be going wrong. I didn't have any comprehension of the technology behind Grunt. Most of the time it was a Node problem, or rather a problem with one of the many packages Grunt was using, and my system not installing things properly...