I wouldn't let the coverstock crack in your first Storm ball alter your decision. I've heard that Storm outsourced the pouring some of there lower end balls to another company (900G?), and that there coverstocks are thinner than their mid and high end stuff, like the Vivid.
For what its worth, Storm owns and pours the equipment for Roto Grip, so treat them as one in the same.
Of the three balls you listed, they are all high end, most hooking, top of the line products from each respective brand. They serve pretty much the same purpose. They are slightly different, but I wouldn't classify any as "better" than any other. I've heard great things about all of them and a few bad things about all of them.
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