I have been lucky to have tried most fins on the market, and I have to agree that the Apollo Bio-Fins are very good, but Force Fin Excellerators kick their arse by putting less effort on your legs.
I, for my sins, am part of a team doing a charity relay dive across the English Channel, and we have been using various fins during training to see what works the best for each member. Now it is each to their own, but after several blasts up and down Horsea Island seawater lake (1km long), most have settled on Excellerators or Bio-Fins.
The reason I opted for the Excellerators? They give easily as much thrust as the BioFins, but at the end of a 2km run (done in 47 mins), my legs didn't ache as much as they did with the BioFins. Now it is all relative compared with paddle fins, there is no effort with BioFins, but halfway through the second klick my thighs were burning a bit. With the Force Fins, I got out at the end and felt i could get back in and do it all over again after a short while out of the water (which is good, as we reckon on having to do 6-8 sessions each).
Now most of us will not be getting in the water and finning like hell for 45-50 mins, and when I am diving normally, I try and fin as little as possible, but I tell you what, doing this training gave me a real insight into the power that different fins generate, and for what effort.
However, forget Force Fins on the surface, unless I swim on my back, in which case I can really motor I just can't see where I am going!
Mark