I’m not a fan of Udemy at all and mostly said my piece about it here: http://forum.freecodecamp.com/t/need-recommendation-for-css-courses/25778/5?u=astv99
Additionally, Udemy as a whole caters to beginners the most, which you said you’re not, so I’d advise against it for you even more. That said, if there are any courses you want to take on Udemy, I’d highly recommend waiting until they do a $10 sale, because those sales come around every so often.
Speaking from my own experience with the major MOOC platforms, for someone looking for more “intermediate” to “advanced” content, I’d recommend primarily Lynda, Udacity, edX, and SitePoint. Coursera has good courses too, but the majority of them are only beginner to intermediate, and lack comprehensiveness (Princeton’s Algorithms course is a notable exception though).
Lynda is really good for getting grounded at an intermediate level, and I highly recommend their Become a Front End Web Developer learning path (which is a set of multiple individual courses). Lynda’s not free for most people, but it does offer free memberships to educational and government institutions, so if you’re a student or federal employee, check with your organization. Some public libraries even qualify for the free membership, so that’s an avenue worth checking as well (I’m using Lynda through a local public library registration myself, so I can attest that it works!).
Udacity is better for more advanced material, and as someone else mentioned, you can actually take individual Nanodegree courses for free (without having to sign up for a full Nanodegree).
I’ve tried CodeSchool as well, which is geared towards intermediate/advanced, but the gamification approach to their content was sort of a hassle.
And I know MOOCs in general are all the rage these days, but sometimes there’s no substitute for a good printed (or digital) book. Not only can a book ground you in a way that will beat any online course, but in some instances a book can also take a much faster time to go through than an online course.