I can't say I've tried them all, but I have Tom's long travel 2.5" coils and they were a vast improvement over the stocks on my '72. I'm willing to bet they are all very comparable though, and might even come from the same manufacturer.
In my opinion, coils are just one piece of the puzzle to making your ride smoother. Over the past year I've added the new coils, dual shock kit and new shocks, and replaced all the bushings in the front end. I can't say that any one of those upgrades was more significant than the other, but together they added up to a HUGE difference in ride and handling.