Wondering the same! Anyone can shed some light on this matter?

i am using hp and it feels better than str in my opinion :L

But think about it...if he has already low on life from a start, basically -5 life and +*% attack, he already starts with low life...when you think like this, doesn't it make sense that it would be better? unless for some reason the explanation works differently...meaning that it doesn't matter how much life you have in a way that "lower life = higher damage", but "more damage taken = higher attack" ?

For me description says - The Lower the Life you have, the higher will the Attack become. Meaning that it doesn't matter how much life you loose, matters how low you life is, meaning that if you would start with 1HP, hypothetically of course, then you should deal tons of damage first round...or that's how I understand the logic here, or OG *s as translating as usual and it actually works the other way?

Currently I made -5% HP and +25% attack, haven't tried much yet, since I only now got him, finally. But if this works better than -nin +life, then I understood the description, despite the fact that developers state that his best attributes are Life and Defense...

I used to think the same, but it fails to explain the damage hidan does in rescue the jinchuriki. Hidan gets a % life bonus in second wave and his damage is unmatched. So i guess more the life you loose, more damage..need to test it out.