mg for mg, it has to go to Epistane, since you can take 100mg of hdrol/pmag during a normal cycle, but 100mg of epi would be a bad idea. Ran athe correct doses though, I would say that they are fairly similar in sides. Epistane has a bigger effect on my blood pressure, but hdrol has a bigger effect on my lipid profile. I would say that they are similar in liver toxicity.
I "feel" less sides on the Hdrol. I also get better gains with it, so it is my go to hormone out of what is legally still available. Epi also tends to dry out my joints more.