I certainly can't speak for all of the brands on the market but I have searched for my Japanese vehicles and my one European vehicle and have drawn a fairly well educated conclusion.
I phoned Ashland Chemical and asked about the Zerex Asian blue and red coolants and was told that they are exactly the same product with diffent colored dyes to accomodate the requests of the OEMs. My Nissan wants blue and my Toyota wants red. I like the looks of the blue coolant so that's what I use.
My Kawsasaki motorcycle uses a product that has 2-EHA in it so at first drain interval I replaced the Kawasaki green coolant with Zerex Asian blue coolant. That was 10 years ago and there's been one coolant change since and all is looking perfect and brand new.
My old BMW uses blue G48 coolant which contains 2-EHA which I don't like but the vehicle is old and I doubt I'll do too many more coolant changes on it. If I were to change it over I'd use the Asian blue. For what it's worth, the plastic cooling system components have all failed exactly one time over the 26 years I've owned the thing. Whether that's related to the 2-EHA or just cheap BMW components remains to be seen. The E46 was known to have cooling system issues and I've been really fortunate with the reliablility of this thing.
And lastly, my old John Deere with a water cooled Kawasaki engine is running some old G12++ Volkswagen coolant that I had left over. The radiator has brass tanks on the side and they're not as shiny and new looking as I'd like but the aluminum engine seems to be in perfect shape. The mower is 30 years old so I really can't ask for much more. It's just experimenting and playing around from here on out.
