Whats everyone running for gears?

Why no choice for 3.73? That seems like perfect compromise combo with the 27" tires on my Duster right now. How come nobody seems to mention tire tire size either? Along with the gear, tire diameter tells the whole story about your final drive ratio and overall gearing.

I have a set of 3.91's waiting to build. Could probably do better with those for racing, but would be too high for highway driving, in the range of a 27" tire, I think.