The most important role of weights during dieting is to preserve muscle. Only weights can do this, whereas diet and cardio can be use to lose fat. I would have thought (particularly if you are doing cardio) that you should continue with the rep range you have been using to preserve muscle.
As to which rep range burns the most calories, it probably matters more what exercises you do, what breaks you take, as opposed to rep range.
For example, squats, deadlifts, lunges and power cleans would burn heaps of calories involving heaps of muscles - just use a Heart Rate monitor on your body whilst doing these, and for me at least, my heart rate ends the set if I am going all out on about 160, which for me is similar to a fast cycle or a fast paced squash game, although slightly less than a 5-10km run. Dips, rows, bench, extensions would all burn a moderate amount of calories and of course isoaltion arm exercises would burn far less than walking.
I don't know if this is accurate, but my polar heart rate monitor (and I'm not suggesting it is heaps accurate) that the 5 v 5 workout 1 for example burns about 400 calories per hour (based on a 70 kg bodyweight), whereas if I just did an arms day it probably would be about 200. I'm not sure how many calories are burnt through the supposed post weights metabolic boost, and whether this differs for different rep ranges (e.g., a rep range like 12-15 with short intervals would I guess be closer to HIT. I guess though if you were going to do high reps + small intervals rest breaks, that would burn lots of calories, but it would frustrate the weights role of muscle preservation perhaps at least IMO. Better off doing normal weights routine and actual HIT)
Out of interest, does anyone know whether the polar heart rate monitor accurate in their calorie predictions, given they do it by assessing your fitness through a fitness test, and then using this in conjuction with your pulse to determine calories burned.