Speargun?

Personally, I would go for the Rob Allen (simple, robust & capable of handling the biggest fish) or the Riffe but I expect they are more expensive.

JBLs:


Rob Allen railgun (above)
Riffe (below)

No euro-gun options (Omersub/Beuchat/Cressi/...)? Working out the length of speargun to get should be a consideration too. I would imagine the water is clear which would suggest a longer gun but you mention diving reefs, which might suggest a somewhat shorter gun; if that is so, I'd guess something like a 100-115cm eurogun/railgun would be in the ballpark. What do other local spearos use?

Looking at this JBL youtube video, the Magnum & Elite look interesting - looks like JBL finally started to update their designs under new ownership.

I don't like the look of the wire/bar wishbones used on the 2 lower models (in video below), they used to be common though & probably still are on low end spearguns. Also check how the spear line is connected to the spear of the various models - some older designs used a sliding ring - looks like the Carbine model here still does. However, some of the models tie-into shark fins - which is very good. Also they use cheap, powerful bulk rubber & provide proper muzzles for that. I'm not convinced by some of the bolder claims in the video but the Elite's s/steel trigger mech. certainly looks impressively sturdy. Also, I notice some of the higher model are also using dyneema wishbones (quiet, finger-friendly, simple, cheap, good - why wouldn't you).
Yes, I see what you mean, the Elite & Magnum models do look interesting - esp. the Elite. The Explorer model is almost there too, pity about that wishbone - probably allows them to use cheaper spears and likely works well enough.