Straight blades I've used: Davie's Matrix Fins, my Cressi 3000's, Cressi 2000's, and O.ME.R. Milleniums.
Angled blades I've used: Spetton plastic and my new Edges.
I'd like to note that Carbon fins are going to be the best in terms of deep diving performance. There's just no way around their High Modulus (Stiffness) capability. You can use a lighter blade to get the same stiffness than say fiberglass. That means less energy is spent on inertia to just move the fin and more transferred to propulsion. Fiberglass is still the best option for me because it is durable while having better stiffness characteristics than plastic.
With that said, obviously the biggest factor is skill.