I was going through the same situation about a month ago.
I discovered HI while searching for the best of the best khukuris and parangs. I learned that HI is a true fair trading business that has actual human interest in the people who make the products, their culture and hard labor showing in every item made. That said, it was a mad ping-pong between which model would be my first and I was in the same boat as you looking at the Chiruwa, 20" AK and the M-43. I went with the Chiruwa Ang Khola and was sent one at 16" with a satin finish.
http://www.bladeforums.com/forums/sh...ruwa-Ang-Khola
I made this decision because I wanted something in average length, not a giant but not small, I wanted a "mid-ranged" HI blade to really get an idea of how it felt and performed before going bigger or smaller.
The CAK that Yangdu sent is so radical,,, such an intense piece of steel. I am 6'3 and find the size of this blade to be perfect for just about anything big or small. It's warrantied use as a pry bar pushed my decision over the top and I can use with one hand comfortably where I have seen recent reviews of the M43 being used with two hands. IMHO the Chiruwa Ang Khola is an ideal first blade from HI and respectively a unique item in their line of products.
My next two HI blades will be the HI Farm Knife (as I love a parang style) and then the AK Bowie. For a second khukuri I am looking at the 20" AK (because I like the fullers better on this model then M-43) or perhaps to find an older smasher or bone crusher,,, although I am sure that when I am ready to order my mega-beast I will have changed my mind again!
good luck, let us know what you go with and be sure to throw up a review!
cheers