I am going with Chris Cox...
Becuase of all the trainers out there that I have seen he is the less pushy about 'ground work' out there.
He has the ability to get on and RIDE the horse without an hour of ground work. He does everyone most people do on the ground work right off the bat in the saddle...becuase he can...
Of course, he does some ground work stuff, and pushes people who cannot ride like himself to do ground work... but that guy can sit with the best of them.
The 'winner' of the road to the horse is the guy who's horse rides the best in the end.
Not who's horse can stand on a stool, not who's horse loves him the most, Not whos horse will stand quietly while you poke at him with a stick, not whos horse can free jump a picnic table. If that were the case PP might just win.
Clinton Anderson sure can ride too, but I think Chris Cox gets better results faster. The last CA clinic I went to his 'apprentice' sat on the 2 year old colt starting demo horse and rode it... that made me question him a bit.
Both those guys have a great program though.
I would pick Clinton for a beginner horse owner and Chris for the advanced horseman looking for more.