Welcome to the eternal debate. I asked this question as well and got a variety of answers.... Here's a summary of what i got out of earlier posts:
-weight and length - the optimal will vary person to person, i decided i wanted something around 15" so i wouldn't get my pants dragged down and that wasn't too heavy for multi-day treks
-The knife design itself... BAS, AK, CAK (though this weights slightly more), and the WWII were all recommended.
-Siru's, Kobras, and other thin, light knives were discouraged because you need alot more length to get the same chopping potential as the earlier mentioned knives.
-I decided an 18" was too big for what i had in mind, so i was/a, looking for something between 15" (BAS, AK) and 16.5" (CAK, WWII, maybe an AK)
-Similar idea with weight... i wanted something around 1.5ibs, so that eliminated alot of stuff.... like AK's over 16.5", most CAK's...
My two cents would be figure out what length and weight you want in a kuk, then see what knives are left in the equation. Really helps eliminate alot of the deliberation.
That said, a final point.
All HI Kuk's are wonderful. Whether you get a WWII, BAS, or AK, all have people who swear by each of them for the tasks and roles you have in mind. Any will serve you well, any will work well. You can't make a bad decision in choosing a kuk from HI
