I think the iPad will be the long term winner here. Legacy OS's are just way too reliant on keyboard / mouse. Having owned a Surface Book, I can easily say that the tablet mode is not workable with the software ecosystem that exists. You can mostly make it function in limited cases, but outside of a small handful of programs built specifically for it the experience is poor.
On the other hand, the addition of a keyboard just makes the iPad even easier to use. Using a mouse is slightly more awkward since you can't use gestures, but you can always fall back to the screen that's right in front of you. The extra precision is overkill, but it isn't painful.
Another layer to add in the tablets' favor: kids these days are growing up using phones and tablets. That's the way they interact with computing technology. It will be increasingly easier to convince these new generations to buy something that's familiar, but with some extra power and utility, as apposed to something that is foreign.