Turner HD's are comparable to Gorilla both in strength and price ($400 each). Turner EVO's will run you $650 each, but have a 2 year no questions asked warranty. According to Turner, in the 3 years they have been out there has been no warranty claims. Evo's can only be run on the rear tho.
My second choice would probably be Rhino ($200 each).
Over the last 1-2 years, Gorilla axles haven't been as good as they once were. When I was researching axles, I found lots of posts complaining about manufacturing / quality control issues with Gorilla axles recently. All the post 2 years or more ago were all positive.