The higher end will give you better milage and less tire wear, but a
worse ride.
Never go lower than the recommended, except off road in soft sand or
mud.
Never go above the rating on the sidewall of the tire.
If you do not mind or notice the firmer ride, the "Highway"
or "Highspeed" sugestion in the owners manual is not a bad starting
point. If you do not like the ride go to 1/2 way between the two
recommendations. If it is still not to your liking, go to a few LBs
above the spec. (That way you will not be below even after losing
some air).