Since the last post to this thread, Adobe has made several Kyle Webster brush preset packs available free to Creative Cloud Subscribers. There is an update to his truly masive Megapack which has close to 500 presets!
Kyle Webster's Concept brush pack contains another 169 really good presets and is also free.
Righht click inside the document window with the Brush tool selected, click on the little cog icon (top righjt corner) and choose Get more brushes
With that many presets it can be hard to find the one you want, so think about copying your favourites to a new group, and remember to use the search bar. A wee tip when searching is to keep it simple. Unless you know the exact name of the brush you are looking for, try not to use more than one search word.