I've been an avid fan of tinny's stoves over at minibulldesign and have a number of them. His Bongo series were absolute fuel sippers, and i was able to get 2 cup boils with less than ~.3 ounce of alc, under optimal conditions and with a windscreen. However, im not gonna lie, his stuff is not simple, and theres a lot of parts involved, which to me is just more stuff to misplace or lose or break in the field. I saw Javan mention zelph's stoves on another thread, so today, i was doing a lot of research into his work. His stuff is mega KISS, with a lot of his stoves being 1 piece. He builds them for small pots including hieny beer pots, so the flame pattern is perfect.
I like his fancee feest and will probably pick one up in the future.
Its under 1 once, and can do a 6.5-8 min boil on just .5 ounce of alcohol. Everythings built in, including the pot stand, and to me this is a benefit because its all 1 piece
His newer stoves are more durable, and a tad bit heavier
Here's his cobalt blue soloist, lil heavier than the one i linked above, and takes a lil longer to boil, but still same fuel consumption. This one is jetted, unlike the fancee feest and unlike the super stove, which is the last link in this post.
This one is also worth a look. Its his super stove...it takes the longest to bring to a boil, but also burns the longest.
He sells some by themselves, and others in a kit with windscreen. Just click on his store link on the top of his posts.
I've experimented with open stoves, and while i find them super light (b/c essentially its just a tealight candle holder, or a sobe bottle cap, or whatever cylinder shape you can find), i dont find them very efficient. The flame patterns are narrow, but they whip all over the place, and are more susceptible to wind. Also, the alcohol always boils in an open tealight type setup, and likely ends up producing more heat then your pot can absorb ( i could be wrong about this, but i remember reading that alcohol boiling is not as efficient) Seeing as how zelphs stoves are designed for narrow pots, you can get the benefit of a jetted stove, while not having flame loss up the sides.
Hope this helps!