Personally, I believe 2016 was his best season. He may not have put up his best stats that year, but I believe his efficiently was top notch that year and he's not been able to repeat it yet.
I believe the way he played in 2016 contributed greatly to the 13-3 record we had, because he wasn't trying to do too much. He was playing his role to perfection and it paid off.
He's gotten better as a QB, of course, but I loved the way he led the offense in 2016. That might be my personal preference though.