I've been using the Mares Avanti Quattro+ for close to 10 years now. Great for diving in currents. The effort to output ratio is impressive. They're slightly negative making them great for women given that many of us tend to have positively buoyant hip, which becomes tricky to deal with as your dive progresses and tank gets emptied. The Apeks RK3 is also another great option. Great effort to output ratio. Light on the legs and the propulsion is amazing!