I'd take AO 2017 over 2014. Nadal would have 20 slams now, 1 more than Federer. Plus if Nadal had won that I am sure he would have won a few of their subsequent matches, especially Miami 2017 where Federer beat him by playing just average tennis. Nadal checked out mentally, the AO final was still on his mind. Even at IW you don't know if Federer would have played the same way if he had lost the AO final. AO final was the turning point in their late career rivalry.
That's actually a very good post. AO 2017 final would be a close second. It turned around the Fedal rivalry. Fed beat Nadal 5 times without losing a set. It gave Fed a new spark.
If Nadal had won AO 2017, maybe Fed doesn't RISE in confidence and win AO 2018, Wimb 2018 etc.
That being said there is a reason that AO 2014 Final has been said by Moya, Toni and the Nadal camp as the WORST loss of his career. He was a SOLID SOLID favorite in that match, so the loss is hard to accept.
In a way, Nadal never FULLY recovered from that loss. Even now. I don't think he will EVER be the player he was in 2013/early 2014.
It also caused a downward spiral for Nadal and he lost 2 years of prime tennis. He was so bad in 2015 - that he was thrashed by Novak in Paris - in Rafa's own backyard. In straight sets, no less. Proceeded to lose to Fog after leading 2 sets in the UsOpen.
Then in 2016, Rafa got injured at the F.O and couldn't do anything there.
What would have happened had Nadal won AO 2014 Final? He would have a double career slam - which Novak/Fed do NOT have (and might never have).
He would have won more slams in 2015/2016. He would generally have been more confident of his game, his body etc etc. He would have likely crossed 20 slams by now.