Recommendations
Warning!
It is very important to note that although all of these clinicians believe in similar principles of horsemanship (thus they know what to do), they vary somewhat in how they put these principles into practice. Their communication system of aides and incremental steps (how to do it) are consistent whether they are on the ground or in the saddle so it works for them. But you can't mix and match how to do things. It's a self-contained system. A hodge podge would confuse your horse and bring out undesirable behavior and responses.
So what's the answer to this dilemma?
You have to do what feels right for both your horse and yourself. Try a number of methods out in their entirety on one horse for a period of time and see how you and your horse get along with it. If it doesn't feel right, try another one of these horsemen's progam. I've actually ended up using a hybrid adaptation of Jim Durling, Bob Loomis and Clinton Anderson schooling and riding methods that complement rather than conflict with each other. On the ground, I use a hybrid adaptation of Chris Irwin, Pat Parelli, John Lyons and Marty Marten methods that complement each other and is consistent with the riding methods I use.
Jim Durling
I would recommend taking lessons or attending any clinic given by Jim. Not only does Jim get high performance out of his horses, (and wins just about every reining show he enters!) he schools his horses using horsemanship principles and practices that keep his horses willing and highly responsive. He's firm but fair. If I knew half of what he does about schooling, I'd be alright.
Bob
Loomis
I got a lot out of Bob Loomis's book Reining- The Art of Performance Horses. He presents his entire program in a step-by-step manner right from starting two year olds to finishing a reining horse. Lots of pictures and diagrams. His videos Program For Training the Reining Prospect and Program for Training Young Horses bring the book to life. I think Bob gets right down to the essence of things and thus is able to keep things simple for both you and your horse. I was particularly struck by his thoughts on riding horsemanship. Basically he states that although there is an ideal riding position, it's more important for a rider to be relaxed and supple in the saddle and thus more in balance and rhythm with his horse than it is for a rider to put himself in a unnatural riding position that may make him hold himself in a tight manner and thus not flow with his horse quite as well. You can buy his book here. You can buy his videos here.
John Lyons
John Lyons has been called America's Horseman. I have most of his Symposium videos as well as his video Controlling Your Horse's Speed, his Ground Control and Riding Control Manuals/DVD and his book Lyons on Horses. I recommend all of them, and any other products he or Josh Lyons have on their website. You can't go wrong with them. Solid horsemanship.
The Symposium are geared toward teaching the core principles of horsemanship - what's your horse thinking and feeling about some particular thing and what's the best thing to do to help him through that thing. The Ground and Riding Control Manuals/DVD provide step-by-step schooling instruction as does the Controlling Your Horse's Speed video. I rode using John's communication system for a year. John is a reinsman. He uses his reins to not only position the head, neck and poll, but to control all other body parts and the feet as well. I prefer to use my legs to position the shoulder, barrel and hip so don't ride using his system of aides any longer. But that's just me. You may love it. See http://www.johnlyons.com.
Pat Parelli
You've got to hand it to Pat Parelli. He really breaks down the principles of horsemanship and presents it using words and phrases that are both understandable and memorable. As far as I can figure, he is the one that really popularized the concept of horsemanship. For awhile there, it was a lot of fun following his program. I spent a lot of time playing with my horse on the ground and really learned how to develop relationships with my horses. I used to ride bareback out in the fields with just a single rein rope halter on my horse. It felt very free. Although I don't put into practice some of the principles the way Parilli does, I recommend you go through his program up to Level 2 at least. Just be careful to tune into your horse's emotional state and not push your horse into his flight response or drive your horse's head. See http://www.parelli.com.
Chris
Irwin
In my opinion, Chris Irwin is a master horseman. From his tapes and clinics, I learned how to read the body language of horses and how to become my horses leader. I start colts using his methods, round pen using his methods and de-spook using his methods. I learned the importance of being in balance and balancing my horse both on the ground and in the saddle. I believe his riding methods are the absolute best way to ride ANY horse but, to be honest, I didn't enjoy riding that way. Not my style. I use his riding principles but just not his practices. (When riding a problem horse, I do use his riding techniques since they are the only ones that work for me.) See http://www.chrisirwin.com
Clinton Anderson
I school my horses using the communication system and exercises in Clinton Anderson's Riding With Confidence Series I-III (with a few exercises added in that I picked up from Jim Durling and Bob Loomis). Clinton also explains the horsemanship principles involved in his practices and demonstrates common horse and rider problems and solutions. If you follow his step-by-step program, your horse will improve his performance and you will have learned tremendous schooling horsemanship skills. I don't have his Ground Exercise Series but I'm sure it's very good as well. See http:downunderhorsemanship.com.
Marty Martin
Marty Marten has written an excellent book on Problem Solving which contains step-by-step solutions to common everyday problems and the horsemanship principles behind these solutions. I'd go to one if his clinics in a heart beat. See http://www.martymarten.com.
Ray Hunt
My understanding is that more than 20 years ago, Ray Hunt, along with Tom Dorrance, were among the first to look at things from the horse's perspective and figure out a set of new horsemanship principles that has since formed the basis of the today's horsemanship movement. His book - Think Harmony With Horses, is a must read. It's all there. See http://www.rayhunt.com.