I think the A2 and 2017 are much better value purchases and unless you want a pencil you should question why you need the pro. Just for a name or a CPU you dont use to the full extent?
My preference would be brand new 2017 model. It still has 1 year warranty. Plus, you never know if the previous owner ever used their Air 2 in the john.
Still a great device. I think the biggest selling point for the Air 2 is the laminate display and it's a thinner device as well (Even though both devices are relatively thin.)
Not a bad deal at all. My A2 is 16gb and was fine. I always had about 3-4 gigabytes left open. With a 16gb iPad you just have manage memory carefully. Use iCloud and watch how many apps you have on it at one time and you should be good to go. Hope you enjoy your new purchase.