Cressi Killer for me.
Small & stainless on a sheath on my leg. Doesn't stay sharp like the titanium - but I don't care and sharpen after every dive anyway using a whetstone and oil.
These knives are not expensive at about £15 I think.
The chances me losing my knife is pretty high, I've lost two in the last 4 years - depending on what kind of fishing, and, the type of knife sheath, I don't think it takes much to lose them - a bump into a rock, a drag through some kelp, dropping it with a struggling fish, and my personal favourite - not re-engaging the sheath properly - doh
By the way - as a matter of interest - you really don't have to spend a fortune on overpriced purpose built knives - I know some of the older spearos used to use a kitchen devil stuck in a piece of hose pipe - may be no good for larger fish but would probably be fine for UK fishing.
