I voted for opposed pairs. The way I do personality stats in my story, I let the reader choose the actions, but let the reactions after the choice be based on the personality stats.
I don’t exactly have a “set personality” at the start, but I have variables called “traits” that boosts a certain personality stat. So you can choose to be extroverted for example, which makes choosing introverted choices have less of an effect to the stat overall.
I’m disappointed my What if opposing stats actually used two variables? thread didn’t gather much interest. Using two variables for opposed stats basically functions like fairmath, so your earlier choices have a greater effect on your personality, while later choices will have a diminishing effect as time goes on.
I haven’t really tested how well it holds up since I’m still fairly early in my story, but I figured I’d bring it up. 