I think Valby will have the better PRs in the long run. But we need to temper our expectations a lot and quickly.
I hate to say it, but for me, women's running has kind of been ruined. I am not a big fan of the "everyone is doping" theory but honestly, with times like 3:49, 14:00, sub-29, and 2:09, there is NOTHING an American runner can do to be relevant in the coming era.
Remember when Jordan Hassay was trying to break 31:30 minutes in the 10km? She never did. Remember when she tried to break 15:30 in the 5km? She did it! 15:28! That is just "quaint" in the current era.
But getting back to Valby and Touhy... I don't think either of them can run the kind of kind of times we see today; and sadly, the next decade will be full of even more "insane" results. The coming wave of athletes will make everything American women do sort of irrelevant. It reminds me of how it was for American men in the late 1990s.