Thats a good question, one I was pondering asking when I got my DB7K last week ... In that time I have tried a few and settled on Hydra Achilles - The downloading of updated/latest S*ftc*ms and k*ys is ace. I think my second choice would be PP. I had some problems with SF/RU images, which may have been down to me rather than with the images; I will try those again one day.
Try them all. Play & experiment. Let me know which one you preferred ...