From what I've seen (which is not a lot in the last ten years), they are basically the same.  Some proprietary differences in additives and combinations but I have never seen anything to indicate one is clearly better than the other overall.  But again, my direct experience with both is over a decade old.  Buy a few a tank of each, see what you think.  Post your results.
I would avoid most other comparisons because like so much else today, it's pretty partisan.