This is most likely too broad of a request, but I figured since posts like these:
Best Sets of Lecture Notes and Articles
are allowed to exist here, I might as well try…
I like learning from slides. A lot. This is perhaps because of these (perceived by me) advantages:
They usually contain a fair amount of illustrations (and I love contemplating on pictures showing the math in action, it really gets me to think).
They don't have too much information on each individual page, which I think helps in highlighting the important bits, and in concentrating one's focus on one important thing at a time. (This also helps one avoid missing out on important information, because it usually stands out on slides, unlike in books where it may drown into obscurity in the wordy exposition)
They are usually much easier to browse / scroll through than books or lecture notes, much thanks to point 2. This makes searching for relevant information comparatively easy.
Wordiness is mostly constrained to a minimum, meaning that I, the reader, can / must do a little thinking on my own to fill in the missing links, keeping my mind active throughout the reading experience. The lower density of words also offers a lower threshold than those of books and notes in terms of how much energy one has to invest to get going, which is a big plus in my book.
Slides can be even more personal than lecture notes, and even straight-up lead the reader through the subject by asking leading questions, do some work / surveying, answer the questions, and then maybe move on. I like this style of learning, since the steps taken in the slides are usually well motivated to not lose the reader. The slides become my "personal mentor", so to say.
With all of this in mind, I would like to find well-written slides from which I (and others) can learn mathematics (and / or neighboring stuff like theoretical comp.sci / physics / chemistry / biology). I have no preference in terms of subjects, anything goes as long as it is within the scope of this SE site. Think of this as the "Slides only" equivalent of the above linked post. Finally, I only want slides, no corresponding lecture videos or the like, since I can never watch those through anyways.
For a small start on this list, I think X.Viennot has made some very compelling and beautiful slides for a course called "An introduction to enumerative, algebraic and bijective combinatorics", which are retrievable from the course web page: http://coursimsc2016.xavierviennot.org/contents.html
Further, I believe many MOOCs on Coursera and EdX have / have had good slides up for downloading, although I'd need to take some time to filter out some courses with good slides.
