We don't have a lot of options here in my area. I've cooked a few of the Excel Selects with no bad experiences yet. I'm making the assumption that you are referring to full packers?? I just try to pick one with as little a fat cap as possible,,, I want the flat end to be as thick as possible and as close to the point thickness as possible,,,, and I try to insure that the brisket is loose and flexible ( or floppy ) and not stiff. It is very hard to find a brisket at a grocery that has all those requirements,,, but 2 out of 3 will do.
As long as the technique is there,, everything should be just fine for eating brisket.