Simpson is the favorite. He has a ridiculous record on this course. Something like 9 top 10 finishes in his last 11 starts. He won in 2011, and he has finished in the top 3 each of the last 3 times he played in this event. Zalatoris is the sixth choice in the betting odds (28 to 1). He needs to win to qualify for the Fed Ex playoffs (which is stupid as he would've accumulated way more Fed Ex Cup points to qualify, but he didn't get credit for his PGA results because Zalatoris didn't have his tour card). Lots of top players are skipping the event because the playoffs start next week.
FWIW, Bill Haas is in the field as well. He had his best finish in a long time in the Barracuda last week, but would need to win the Wyndham to make the top 125. Not sure if his past success on the tour qualifies him for the PGA tour for next season (which starts in 4 weeks) or if he will have lost his tour card after this event.