If you want stiff, negatively buoyant, powerful AND SUPER COMFORTABLE fins, check out the new Mares Power Plana. I come from Jets and shifted to the Mares Power Plana due to its Power and Comfort. The foot holes are contoured for a human foot vs a brick. The Bungee heel strap are awesome, super easy to put on and very secure vs typical steel spring heel strap. But the best is The Power and speed it gives you while pushing doubles with 2 deco bottles is almost 2x what my Jets gave me. Reverse back kicks is a breeze due to its high side walls. The distance traveled on One frog kick with the Mares is almost 2x further than what I'd get from Jets.
But be prepared. It's Heavy. It's very negatively buoyant. It's stiff. And It requires very strong legs to get the most out of it. Highly suitable for Tec Diving.