Most of the major brands out there the only real difference I've seen is the top moulding being slightly different. Other than that, GM generally uses about 5 different brands to make their glass, so if you get Gaurdian, Pilkington, PGW, FYG, Saint Gobain, or Crinimex it will be from the same companies that make them for GM.

 

4 YRS OLD 08 @102k still orig and only got 1 small chip.