There are different forms of toxicity.
Winstrol raises LDL while d-bol increases blood pressure. But in terms of the effect of the 17 AA, I believe a mg of 17AA is a Mg of 17AA.
True, I've heard that Ox is less toxic but I've alo read studies that show HIGH dosages of Ox are MORE toxic. So the reality is probably somewhere in the middle. What doesn't make sense in regard of one being more or less toxic than another is the fact that the 17AA process has nothing to do with the drug itself. Simply put, it blocks the liver from breaking it down which in turn forces the drug through many mrore passes in the bloodstream. It's THAT process which stresses the liver and can cause damage.
One more thing: The liver is pretty resilient -- for a while. And a slight elevation during AAS use is normal. If you have NO elevation after a month the gear was either fake or underdosed or you took less than 25 mgs a day. This is another reason to keep duration short. Once the liver is stressed, it deteriorates quickly. And spare parts are really hard to find.