I am fortunate to have khukuris by all of them, and they all have their points as has already been pointed out by Munk and others. FWIW, my take: Bura has been doing more and more traditional stuff with standard bolsters, and his blades and handles are usually excellent. Sher is the one that comes up with the great Manjushris and Trisuls and Jure models and Bag Bhairabs and Bob White Bolo and other eye-popping new ideas like that curved Sher Special that Dean snagged the other day, and his Villagers are great.
Kumar is responsible for some outstanding work and made my 25" Malla and Chitlangi, both of which have about the finest workmanship I have ever seen, but has very occasional (usually minor) QC problems otherwise from time to time. Amtrak did good all around work as well, with perfectly formed blades and handles, and his knifes were always so polished that they needed a bit of sharpening to be users, but I'd rather have that that a sharp poorly done blade.
I only have two Sanu blades that are good, but seem a bit heavy, and the work overall is passable but not up to what the others are doing right now. The Kesar, Shankar, Dharan and ! kami examples I have are excellent work but with only a couple of each YMMV. The Y.B. kami is Sher, I'm absolutely convinced of that, so don't know why the separate initials.
Overall though, and this is not denigrating the A+ quality work of the others, but I think Sgt. Karka's work is the best. Frankly I don't think there is any contest IMO, and his work is hands down flawless. I have a 19.5" chandan / chainpuri styled handled WWII from him that is a joy to hold. He also did two Samsher's, a 20" 40 oz. and a 17", that were the only ones I know of from him, and I was able to snag the big one but not the 17", that some other lucky forumite got. I sincerely hope he or she realizes what they have, and I would gladly add $50 to their purchase price and add shipping if they ever wanted to part with it. My 20" was one big razor out of the box, with a standard bolster, no cho creep, perfect handle and buttcap and a scabbard that fits like a glove.
I have seen careful traditional work from Bura and Sher that rivals his. They both surprise the hell out of you sometimes, and I wish someday I could actually talk with Bura and understand why he makes the choices he does. Why sometimes the standard bolster, and sometimes not? Same with the chos.
For instance, on 8/15 he did a a Village BGRS which in my opinion is the single finest knife he has ever done (and it sold for $75!!!

) No cho creep, standard bolster, and a gorgeous grey horn _chiruwa_ handle! Of all the knives to miss. I am still kicking myself.

George in Greece got it as his first HI knife. See it at:
http://www.bladeforums.com/forums/showthread.php?t=360431
If he did more of these rather than the larger knives with large habaki bolsters and heavy cho creep, that would be great, but then he turns around and does the Salyans which are of course totally traditional and immaculate; mine are perfect in every way.
Maybe it's because Sgt. Karka does so few that he pours his whole heart into them? I don't know, but whatever it is, it works for me. Now though he mostly does biltons and occasional dhankutas, and anything over 12" is unusual for him.
Bottom line, I would order any knife sight unseen from HI's current crop of artists, and feel confident about my purchase.
Regards,
Norm