Like the article says Gulp is easier to read but harder to write whereas Grunt is the opposite.
I'll stick to Grunt until I can confidently write a Gulp file.
It doesn't just apply to writing Gulpfiles, but also to extending the functionality. Extending functionality in Grunt is much more straightforward in the sense that you just write a function.
With Gulp, you need to know your stuff in order to write a reasonable task, and the fact that Gulp tasks run asynchronously by default can get tricky, too.