I'm no expert, but I'd say the two on the right are absolutely pristine examples of M43 khuks. The karda and chakma are the appropriate type, as are the sheaths and frogs. You really don't normally see WWII era khuks in such great shape, especially the sheaths. They appear to have every detail correct as best I can tell in the pics. The counter sunk rivets and handle rings, two fore and three aft, are the hallmarks, but even the chos on these match my example. Many, if not most, M43s were not marked, so don't worry if they're devoid of markings. I don't have a clue on the dui chirra looking khuk. It looks very nice. Berk or Spiral could probably offer some info on that one. I'd love to know the purchase price if you feel like sharing it.
The original M43 is a sweet khukuri. It is light and fast. It would be a great combat blade. As an aside, Pioneer did not make the M43. No one seems to know who did for sure, though it's not for lack of research. Pioneer Calcutta made Mk. IIs, which were british military issue khukuri, and of which the M43 is a variant. I have another wooden handled private purchase/commercial type Mk. II which has some of the typical M43 characteristics, as well as a matching sheath and karda and chakma. But it's different enough to be sure it isn't an M43. Honestly, the M43 appears to be a mystery. Some things about it point to maybe small unit issue, but it doesn't seem to have been issued widely. Or it could have just been a commercial variant. Either way, they are some of the highest quality Mk. II variants I've seen. Hopefully Berk and Spiral will chime in, as my knowldeg is very limited. It's a fascinating khukuri for sure. Take care.