Which classical trainers are most associated with exceptional piaffe and passage?

Several classical trainers across different eras and traditions have become particularly associated with exceptional development of piaffe and passage, either through the extraordinary quality of the horses they produced or through their influential writing and teaching about these movements. Nuno Oliveira, the Portuguese classical master who trained into the 1980s at his school near Lisbon, is perhaps the most revered classical trainer of the twentieth century for the quality of his piaffe and passage — the lightness, expression, and apparent effortlessness of the horses he developed in these movements represented a standard that few have achieved before or since. His students and those who observed his work consistently describe the piaffe of his horses as the most complete expression of what the movement should be: perfectly in place, maximally collected, genuinely relaxed, and executed with a quality of brilliance that reflected the complete development of the horse's collection over many years of patient gymnastic work. The Spanish Riding School in Vienna has maintained standards of piaffe and passage through its Lipizzaner stallions for over four centuries, and the school's classical tradition represents the most continuous institutional transmission of what these movements should be, with each generation of Bereiter trained to develop the movements according to the school's inherited principles. Alois Podhajsky, the director of the Spanish Riding School through the mid-twentieth century and the author of several influential books on classical dressage, is associated with high-quality piaffe and passage both in his own riding and in his documentation of the school's methods. Among contemporary international competition trainers, several German and Dutch trainers including those who have produced multiple Olympic and World Championship horses are associated with exceptional piaffe and passage at the competitive level, though classical critics sometimes distinguish between the competitive expression and the classical ideal.