The 345/6 has sold more than the 777LR variants but perhaps not enough to be decisive. And as Joni correctly said, neither is selling very quickly.
I personally believe it's a niche aircraft like the A380 though with a larger niche or course. The problem with these aircraft though, particularly the B777-200LR and the A340-500, IF and only if the Sonic Cruiser goes ahead, they will be competitively disadvantaged. However, if the SC doesn't go ahead, I personally believe there will be more orders as airlines go for longer, thinner routes or go for mega-hubs (which obviously will be the domain of the A380).
It's been stated that the B777 has an advantage because of its good customer base. This is true, though Airbus has been wooing customers away from Boeing's other products and hence give their A330/340 products a better shot when and if the airline expands.
The main problem with the B777LR products is that only the GE-90-115 series of engines are offered. Similar problem for the A340-600 which will only be using RR Trent 500's. Such inflexibility means that airlines are still doing cost-studies as to which aircraft is the better buy, if in fact they do buy them.
M88, 722, 732, 733, 734, 73G, 73H, 742, 743, 744, 752, 762, 763, 772, 773, 77W, 320, 332, 333, 345, 388, DH8, SF3 - want