Final answer:
Josquin des Prez and Guillaume Dufay are the composers at the head of Tinctoris's list of talented composers from the mid-to-late fifteenth century, renowned for their contributions to music.
Step-by-step explanation:
The two composers at the head of Johannes Tinctoris's honor roll of talented composers of the mid-to-late fifteenth century are Josquin des Prez and Guillaume Dufay. Tinctoris, a notable music theorist of the Renaissance, recognized these composers for their exceptional capabilities in the realm of sacred and secular music.
Josquin was admired for his expressive compositions and mastery of contrapuntal techniques, while Dufay was celebrated for his innovative approach to harmony and the structure of the Mass.