[Buzz]

When asking to define the "premium" brands, bear in mind that different people have differing priorities so you can end up with a huge range of opinions. In the general Cobra replica market, "premium" is commonly defined by products that most closely replicate the original Cobra in body appearance (accurate lines, stance, wheel-to-body relationship), dimensions (wheelbase, ride height, cockpit size,etc), suspension (IRS vs. live axle, pin drive wheels), drivetrain (set up for correct engine and transmission) and overall quality of construction.. By these measurements, some of the commonly accepted top brands currently in production are - in no particular order - Shelby, Kirkham, ERA, Unique, Superformance, Premier Motorsports. Within this group, Shelby and Kirkham offer aluminum bodies which places them in an even loftier bracket than the other premium brands.
Hurricane is a newer, budget oriented contender that offers an IRS option and has gained growing respect and support. FFR is extremely popular and generally regarded as an attractively priced way to get into the Cobra hobby using the "donor car" concept. They have a nice, accurate looking chassis but their body is known more for its "perky butt" shape than original appearance. The general consensus is that with a little extra money and effort, an extremely nice car can be built, rivalling the "top" brands in execution. A new upcomming body using a digitized and CAD-rendered copy of the famous 198 mph original car driven by the late Dick Smith is, depending on execution and details, likely to place FFR squarely among the "premium" brands.
There are other replicas that do not accurately replicate the original car in size, shape and appearance and have gained a following among those who are less interested in pedigree or history and want a nice, Cobra-like hotrod with more space and (in some cases) modern appointments and suspension. Manufacturers like Backdraft, West Coast Cobra, Classic Roadsters and others use the pure, functional beauty of the original (eg: flared, widened fenders to accomodate and enclose larger racing tires) as a series of "cobraesque" styling elements to create a different looking car with a longer and/or wider and/or more bulging fendered appearance. They offer more legroom, etc, but in the opinion of those who fanatically love and admire the low, tight symmetry and proportions of the original, the shapes are almost unbearable to look at. To the owners who choose these brands and care little about original lines, they are regarded as roomier, more comfortable and - in their view - dam' fine lookin' hot rods.
If you are seriously considering buying a used Cobra, in addition to the top brands mentioned above, there are some premium brand cars that are no longer in production but well worth looking out for. Contemporary, Hi-Tech and Gentry come to mind and I'm sure there are others.
To each his own and there is certainly lots of variety out there. Establish your budget and your priorities and get set to enjoy YOUR version of one of the most beautiful and exciting cars ever built.