I'm a rack-mounter, so specific info from me is bogus....but the general rule is fewer teeth=more torque, higher#teeth= more speed.
The drawback on the highest is it takes more ooooomph to get rolling, but if you are in shape, and since you live in a pancake world, that won't be as important as it is to the hilltoppers.
One thing to keep in mind, this being your first, you might-( probably will ) fall victim to the addiction and start on bike #2 within a month.
So think "aftermarket", maybe stay a few notches beneath the maximum number of teeth, so an out of shape customer can get it moving and buy it right from under you.