here goes mine:
djokovic’s forehand (watch the 07 us open final and its not hard to notice how massive of a change it was)
wawrinka’s forehand (no need to comment here)
nadal’s forehand
federer’s backhand '17-'18 (that one is questionable, maybe its more due to the larger racquet frame)
he was indeed a more offensive player back then and his forehand was somewhat faster, but aggression in continuously slower courts is degrading day after day. i wouldnt call him a defensive player today but he’s a consistent baseliner outplaying everyone