You should write ES6 these days! ES6 does not only add class sugar, but many many other sweet advantages which will make your life a lot easier :)
As for the question "shall i stick with function way or shall i move to classes", though, I think it's personal taste. You can go the functional way and just put all your functions on a single object which you import from some module. Or you can go the OO way and write classes, which bring a number of advantages (like Mixins) and a number of complications.
Personally, I prefer the OO way, because I like to bundle my data into instances and couple that with procedures. I also like to compose my APIs with Mixins. So OO, for me, is the right way to go in most situations. Don't forget: use the right tool for the right job. Sometimes, it does not make a whole lot of sense to make a class, and just writing the functions is way better.