Unlike many other home appliances, it is not required that dryers display their energy efficiency because there is not a large variance between models.
To keep your dryer running longer and in top condition you may want to keep these things in mind...
Get a dryer with a large lint duct and capture trap and clean it out after each dryer load.
Keep the distance from the dryer to the outside vent as short as possible. You hurt the efficiency of the intake and outtake of air and can cause possible lint buildup in the ductwork that can cause fires.
Make sure your washer is up to its tasks, spinning the clothes well, so there is less moisture for the dryer to extract.
Separate lightweight from the heavier clothing for an even and faster drying.
Consider a laundry day when you can dry clothes one load after another, keeping the dryer from having to heat up between loads.
Look for a dryer that has a moisture sensor, a good reliability record, and, if possible, gas fueled.