I use either a chimney burner made using a 250ml Red Bull can (see Mini Zen at Zen Stoves), or a trangia-style burner made from the same cans, with a conic inner wall and jets around the inner of the pressed dimple.
Both these burners produce a narrow flame that hits the centre of the pan and spreads out, so little heat is wasted up the side. A simple, open cup made from one one these cans also works pretty well, which is a bit disappointing to find out when you've spent ages carefully drafting burners...
The burner that comes with the Caldera Cone is relatively tall (something like 45mm), whereas mine are 32mm tall, and I design my clones to use a 24mm flame gap between burner and pan. These allow me to boil 500ml of water with 15ml of 95/5 denatured alcohol.
I have PostScript design scripts for the conic burner and clone; PM me with an email address if you'd like copies.