I have never been attracted to either of these trainers, or most any big name trainer, because just watching a DVD or a clinic from a bleacher seat just doesn't work for me. My learning style requires that I have a trainer standing in the middle of the arena yelling every bit of my faults straight into my ear, because I thrive with correction the second I make an error. I'm an "in the moment" learner, ha ha. I'm at this weird place where I have enough raw horse experience, but need fine tuning, if that makes sense... 'educational videos' are usually more of a confirmation of my knowledge than anything else, kind of a shape put to what I figured out or noticed on my own.
It doesn't really matter who the trainer is, watching a DVD series just doesn't appeal to me as a way to learn- they do not/ cannot take into account the fact that horses and people are individuals who learn and react differently. You can go through the exact motions that you see on the DVD, but how will you know for sure that you are doing it correctly? It's like learning how to do a proper push up from the internet. You can make it look like a push up, but that doesn't mean it's actually a push up. What if your horse doesn't respond well to what you're doing? How will you know if it's you or the horse? Is your horse disrespecting you, or are they genuinely puzzled? This is really just how I learn, but if a trainer is not handy (which was the case for pretty much all of my life and even now, my lessons are quite erratic due to lack of funds and time) I have found that any help I have ever needed either came from my horses' not so subtle queues/ trial and error experience, watching 3 minute youtube videos to point me in the general direction, or just reading. I have never, ever, felt the need to adhere to a specific training program, especially one as general as the ones from the BNTs.
My sister is getting into Parelli, and she has been adamantly trying to show me videos and convince me that he's worth while, to no avail. The more I watch, the more put off I am- not only by the fact that 90% is purely for marketing purposes and to make him look like the Second Coming of the horse world, or that most of it is fluff and games, but that most of the stuff he does is unnecessary in my opinion and not as effective as other methods I have encountered. (I'm sorry, OP and other Parelli fans, but I really just don't like what I see at all, trainer or horseman... Just my honest opinion.)
And if anyone has had success with either Pat or Clint, I'm happy for you, it's good that you found a method that works for both you and your horse. I just personally don't like either much.
I do like a lot more of what I see from Buck Branaman, though. Not enough to follow him religiously, I don't think there's anyone I care to follow, but I do like him. I like him as a person, a rider, and a trainer. He has much less marketing fluff, he seems to be in it to train people and horses, and that's what I like to see. I'm really not knowledgeable on many trainers, so I really don't have much else to contribute, sorry!