Federer over Nadal. 6-3 3-6 6-1 win in the season-ending tournament featuring 8 best players of the year saw the top two seeds making it to the final for the first time since 1986 (Lendl and Becker). After losing the last 6 of 7 games against Rafa, Roger finally won his arch nemesis. And he won convincingly. Not long ago was he a clear choice as the best player of all time. With recent dominance by Nadal over everybody else the choice has not been no longer that clear. Amazing but we might be witnessing two best players of all time playing each other in the same era. Rafa is 5 years younger but that's a small age gap.
Next year Fed should dominate again. He might even win the grand slam! That is all 4 major titles. The more they play each other the better for us.