head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.

Execution · Competitive PvP
Shot timing and play-calling against opponents who scheme around your habits.

Execution · Competitive PvP
Shot-timing execution against adapting human defense, on top of build and playbook math.
NBA 2K16 leans Execution (Competitive PvP); NBA 2K17 leans Execution (Competitive PvP).
NBA 2K17 leans a little harder on execution, though the gap is small.
NBA 2K16
Shot-stick timing and dribble moves gate every possession
NBA 2K17
Shot meter timing and dribble execution decide possessions
NBA 2K17 leans a little harder on reads, though the gap is small.
NBA 2K16
Online opponents adjust defensive schemes against your tendencies
NBA 2K17
Online opponents adapt defensive schemes and bait plays
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
NBA 2K16
Shot RNG and card packs add bounded randomness
NBA 2K17
Shot RNG wraps the timing meter
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
NBA 2K16
Playbooks, rotations and roster building reward deep study
NBA 2K17
Build math, playbooks and matchup hunting underpin wins
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.