Somehow I missed this thread.
I've long been a fan of Farrell's output, and have all the horror books, and most of the war ones. I've got most of the Superiors, although a handful now appear to be drifting out of sight. The Farrells were for the most part of a higher standard, art wise. Some of the Superior covers are very crude indeed, especially Journey Into Fear. But that for me is part of their charm - they're almost kitsch, like penny dreadfuls. And due to some of the artists presumably learning how to draw on the hoof (those were the hothouse conditions at the Iger Shop back in its heyday) some of the covers are very weird indeed.