These, and the bird and trout sized knives they do, are too small for my hands. Nothing wrong with how Bastinelli makes knives, but these are kinda little.
The straight one is more or less a kiridashi with a retainer ring, so if I ever decided to pick up a kiridashi for crafting, I'd think about this. (Pricy for what you get, but I'd still think about it.) I think it'd be more useful for things like that than the reasons most people carry a neck knife, tho.
The hawkbill blade on a karambit makes it a bit less of a utility knife, so in my opinion most of the most useful karambit neck knives are sort of 'hybrid' -- they have a karambit grip and ring but a more traditional blade. The hawkbill would be best in a survival fight -- they're what make the traditional karambit so effective - so you really have to ask yourself how real you're being. If you're a cop that needs an off hand weapon you can use if someone tries to grapple your service weapon away from you, if you deploy to combat zones, if there are active threats against your life, then sure,go with a hawkbill karambit, bob's your uncle. If on the other hand you have had to open thousands of boxes, envelopes, bags and other packages with your pocket knife, if you've had to slice food, or whittle wood, or pick out a seam, if you use your knife all day long but you've never had to use it in self defense, then realistically just about any other blade shape is going to do better for you.
Given all this there's six suggestions I'd make, in order of cost. The first three don't have the ring, but are extremely easy to grip; the last three have the ring.
1) A CRKT Minimalist or Folts neck knife - they also have a karambit style, no ring but super grippy.
2) A Real Steel Alieneck -- tremendous value, looks evil
3) an ESEE Izula -- gold standard neck knife, not too expensive, can buy versions with a proper handle if you prefer
4) A Maserin 921 - slick and streamlined
5) a Benchmade Thompson SOCP - not a karambit, it's much more of a stabber, but it's amazing
6) a Flagrant Beard Havoc - Rugged. This, like the Benchmade, has a training version available as well, so you can actually train with them, which I recommend if self defense is one of the intentions of buying the knife.
Two cents and change :)