I think Warwick Schiller does great work. I ride English, but most of my attention atm is spent learning about how a horse should be ridden, biomechanics, movement, and things like that instead of training videos. I’m also really big on +R so I’m pretty much always digging for more information on that, as well as horse behavior and how they think and act. Two books that I think are great no matter what discipline you ride are: Recognizing the horse in Pain II: And what you can do about it! By Joanna L Robson DVM, and Tug of War: Classical vs. Modern dressage and how incorrect riding negatively affects your horse’s health, by Dr Gerd Heuschmann. Amazing books. I’ve honestly been all over the place with researching different things, lol. I also love Kathy Sierra and her work with horses...actually I just signed up for her Pain’t science workshop, which is a course about pain science(obviously, lol). movement, and motivation in horses. Heres the link to her course, I strongly recommend watching the videos she has up on her site..just look at how her horses move.https://www.pantherflow.com/ Her course is about to close for enrollment, and you won’t have access to the course or the three videos she has posted right now once she does.
I listen to a lot of podcasts as well, equiosity is a great one, as well as The Feed room chemist and spirit of horse.
Equitopia also has amazing videos on biomechanics and proper development in horses.
Lol, I could go on all day about a ton of really great trainers, books and resources but these are what are coming to mind right now and that I think they are worth looking at!