Reyna since having good aim enables you to get kills consistently and thus unlock the rest of her kit.
Jet because her ult has pinpoint accuracy and is extremely deadly if you don't mind some vertical aiming here and there.
But I guess any duelist will do.
I don't feel like like Omen matches what you're looking for. He has immense outplay potential. You don't want to get in situations with him where you'll need better aim than your opponents to win. You want to surprise people with unpredictable positioning. A good Omen is a nightmare for aal the reasons except good aim.