My spearing fins are Beuchat Mundial Competition fins with tough plastic blades. They are a relatively cheap & cheerful freediving fin over here (£40-£65-ish), with polymer (i.e. plastic/nylon?) blades. Sporasub's products seem to be targetted more at the highly expensive end of the price range (at least judging by some of their RRP/SRPs) - with the sister company Omersub's product line being more in the middle.
That said, I've used mine for more that 5 years and they have taken a lot of abuse (I weigh up to 250lb). I find the foot-pockets very comfortable with socks (year round) and without socks (sometimes in the summer or in the pool). I have heard reports that the foot-pockets suit narrow feet but my feet are not at all narrow - quite wide in fact. I believe they are popular enough that you can get alternative blades from Beuchat [see carbon & camo fibre blades above] & 3rd party replacement blades that fit them (they are different to Omer fittings I believe) - but my original blades are still good, even after many coats of various types of paint (acrylic, oil, enamel, car, house,...).
If spearing, you might want to get a blade colour that is relatively camo in your waters (e.g. black or green). You can paint them but might as well start with a good base-colour
.
Seacsub spearfishing fins seem to be potentially "best buy"/"best value" products at the moment over here in Blighty, they offer several models (which are evolving all the time), e.g.
I believe this is Anthony at Venture Sports in Paignton, S. Devon, UK (sells the neat little Samurai spearo dagger too):
Long FINS Flippers SEAC XPRO - Snorkelling Spearfishing | eBay
Mike's in Bristol (I got my dive booties from him):
SEAC SUB X-PRO FINS Freediving spearfishing 6.5-13 | eBay
Looks like there is quite a choice just from ebay these days:
Spear fins | eBay
This link includes many of the popular choices, for spearfishing anyway:
Scuba diving equipment - Spearfishing fin