During the regular season Wentz was much better than Foles. Foles had one of the best playoff performances in the history of football. His 115.7 rating is higher than any season Tom Brady has had in 15 years of the playoffs.
Mahomes to me is a good QB when guys are running wide open. With Hunt, Hill, Watkins and Kelce the Chiefs probably have the best skill group players in the game. They also have a QB that hasn't been figured out yet.
Again we will see with time, but I think Wentz will be the best. That being said Goff in my opinion is the most likely to win the next Superbowl. The Rams look really, really good.