I would always go for a weapon which has more damage dice. Because in some situations, the minimal damage, thus 1 or 2 more points compared to other weapon types, can mean the difference between win or lose. And you want to mitigate risks in tight combat encounters.
Yeah, my own instincts are to go for the 2D6, but since 1D12 weapons are in the game, I'm wondering if there are players out there who prefer the wild swings in damage over consistency.
