Trying to be objective:
Case for/against Tuohy
+She appears to heading in the right direction, has a track record of performing well at NCAAs (minus last year's NCAA track), and appears healthy. Her team will be contending which typically helps an individual contender. She's from the historically stronger program with the more proven coach/system.
-She's at a point in her career when her year-over-year improvement appears to be slowing significantly, and this plays mind games with athletes. NCAA track may still be in her head. The faster/easier course may not suit her to the extent it does her rivals.
Case for/against Valby
+She's been dominant all year. She is the most talented American-born runner in the field--one of the biggest engines ever amongst US women. She has a team behind her this year. The course/weather will suit her better than last year. She's beaten Tuohy this year. She's healthier than in the past.
-She's been dominant all year. Being too fit, too soon is the NCAA XC toxic trait. Her most recent race was (maybe) less dominant than the rest of her races (maybe). How healthy is she? That gait is a little wonky, but who knows. Her coach doesn't have a history of having athletes consistently ready on the big day.
I think there's a 65% chance Tuohy or Valby wins the race and a 35% chance one of 3 or 4 Africans wins.
I'm going with likelihood to win:
1. Valby 40%
2. One of 3 or 4 Africans 35%
3. Tuohy 25%