interesting question. ultimately, "least out of breath" may need to be better defined to come to a consensus on this.
what qualifies as "out of breath"? certainly if you stay totally aerobic, not using any meaningful amount of anaerobic metabolism, you are not out of breath, right? and if you have used up all of your anaerobic work capacity and faded to the point where you are at your maximum, yet can only run at a pace your aerobic metabolism can support, that would qualify as being completely "out of breath", right?
if that line of thinking is correct, my assumption is that determining the "least out of breath" would be based on some combination of who has used up the lowest percentage of their anaerobic capacity AND at what rate are they burning through it.
i don't think we can come to a valid answer without knowing their current capacities at approximately 400M through 5000M.
my gut tells me it would go like this...