Aerobars. If you want to get the most out of your legs, use the triathlon extension. The type of handlebars affects your wattage due to a contribution to the aerodynamic drag.
For aerobars, this contribution is 0.2914. It increases to 0.307 and 0.324 respectively, for drops and hoods, and it's highest when you are relaxed on the tops, at 0.408. Read more