I can think of at least one other cross no one's mentioned here yet that appears to have turned out amazing: burbidgeae x rc. Could be we just need to find the right species to mix with, or could be we need the right specimens.
Photos?
Agreed about the densiflora cross - that is the only one I've seen that I would consider growing. I did have the ventricosa X robcantleyi and grew it for a year - hoping and hoping it would become more interesting. In fact, it did the opposite - becoming more homely and awkward looking with every pitcher; reminded me of a cross between a giant pumpkin and the baby from Eraserhead.
Agreed about the densiflora cross - that is the only one I've seen that I would consider growing.
: