Some would say Skenes, but hard to count on a pitcher to stay healthy and he's got 4 less years of control if he wins ROY.
Fangraphs sort of explored this question recently in their trade value series. Chourio came in at 25 behind Henderson, Witt, Skenes, Elly, Julio, etc.
But, yeah, of that list I personally would probably only entertain a 1-1 deal for Witt and Julio. But even in those cases I would think long and hard about it.