What brand is the gtx 960

I was thinking of upgrading to a gtx 960 but I was wondering what brand and model gpu is the 2 gb and the 4 gb cards

usually palit or zotac

Do they have a gigabyte g1 edition.

As Keynes said it is usually Palit or Zotac (though no guarantees), so I doubt it'd be a gigabyte g1 edition, if you want a specific brand/version of the GPU then you would need to order said specific GPU from elsewhere I'm afraid.